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@ -2566,14 +2566,14 @@
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<li class="md-nav__item">
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<a href="#1313" class="md-nav__link">
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13.1.3. 常用术语
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13.1.3. 框架代码
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</a>
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</li>
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<li class="md-nav__item">
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<a href="#1314" class="md-nav__link">
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13.1.4. 框架代码
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13.1.4. 常用术语
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</a>
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</li>
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@ -3380,14 +3380,14 @@
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<li class="md-nav__item">
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<a href="#1313" class="md-nav__link">
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13.1.3. 常用术语
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13.1.3. 框架代码
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</a>
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</li>
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<li class="md-nav__item">
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<a href="#1314" class="md-nav__link">
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13.1.4. 框架代码
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13.1.4. 常用术语
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</a>
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</li>
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@ -3470,7 +3470,7 @@
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</code></pre></div>
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</div>
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<div class="tabbed-block">
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<div class="highlight"><span class="filename">preorder_traversal_i_compact.py</span><pre><span></span><code><a id="__codelineno-2-1" name="__codelineno-2-1" href="#__codelineno-2-1"></a><span class="k">def</span> <span class="nf">pre_order</span><span class="p">(</span><span class="n">root</span><span class="p">:</span> <span class="n">TreeNode</span><span class="p">)</span> <span class="o">-></span> <span class="kc">None</span><span class="p">:</span>
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<div class="highlight"><span class="filename">preorder_traversal_i_compact.py</span><pre><span></span><code><a id="__codelineno-2-1" name="__codelineno-2-1" href="#__codelineno-2-1"></a><span class="k">def</span> <span class="nf">pre_order</span><span class="p">(</span><span class="n">root</span><span class="p">:</span> <span class="n">TreeNode</span><span class="p">):</span>
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<a id="__codelineno-2-2" name="__codelineno-2-2" href="#__codelineno-2-2"></a><span class="w"> </span><span class="sd">"""前序遍历：例题一"""</span>
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<a id="__codelineno-2-3" name="__codelineno-2-3" href="#__codelineno-2-3"></a> <span class="k">if</span> <span class="n">root</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
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<a id="__codelineno-2-4" name="__codelineno-2-4" href="#__codelineno-2-4"></a> <span class="k">return</span>
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@ -3623,7 +3623,7 @@
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</code></pre></div>
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</div>
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<div class="tabbed-block">
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<div class="highlight"><span class="filename">preorder_traversal_ii_compact.py</span><pre><span></span><code><a id="__codelineno-13-1" name="__codelineno-13-1" href="#__codelineno-13-1"></a><span class="k">def</span> <span class="nf">pre_order</span><span class="p">(</span><span class="n">root</span><span class="p">:</span> <span class="n">TreeNode</span><span class="p">)</span> <span class="o">-></span> <span class="kc">None</span><span class="p">:</span>
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<div class="highlight"><span class="filename">preorder_traversal_ii_compact.py</span><pre><span></span><code><a id="__codelineno-13-1" name="__codelineno-13-1" href="#__codelineno-13-1"></a><span class="k">def</span> <span class="nf">pre_order</span><span class="p">(</span><span class="n">root</span><span class="p">:</span> <span class="n">TreeNode</span><span class="p">):</span>
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<a id="__codelineno-13-2" name="__codelineno-13-2" href="#__codelineno-13-2"></a><span class="w"> </span><span class="sd">"""前序遍历：例题二"""</span>
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<a id="__codelineno-13-3" name="__codelineno-13-3" href="#__codelineno-13-3"></a> <span class="k">if</span> <span class="n">root</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
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<a id="__codelineno-13-4" name="__codelineno-13-4" href="#__codelineno-13-4"></a> <span class="k">return</span>
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@ -3794,13 +3794,9 @@
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<p>复杂的回溯问题通常包含一个或多个约束条件，<strong>约束条件通常可用于“剪枝”</strong>。</p>
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<div class="admonition question">
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<p class="admonition-title">例题三</p>
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<p>在二叉树中搜索所有值为 <span class="arithmatex">\(7\)</span> 的节点，请返回根节点到这些节点的路径，<strong>要求路径中只存在一个值为 <span class="arithmatex">\(7\)</span> 的节点，并且不允许有值为 <span class="arithmatex">\(3\)</span> 的节点</strong>。</p>
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<p>在二叉树中搜索所有值为 <span class="arithmatex">\(7\)</span> 的节点，请返回根节点到这些节点的路径，<strong>并要求路径中不包含值为 <span class="arithmatex">\(3\)</span> 的节点</strong>。</p>
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</div>
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<p>在例题二的基础上添加剪枝操作，包括：</p>
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<ul>
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<li>当遇到值为 <span class="arithmatex">\(7\)</span> 的节点时，记录解并返回，停止搜索。</li>
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<li>当遇到值为 <span class="arithmatex">\(3\)</span> 的节点时，则直接返回，停止搜索。</li>
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</ul>
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<p>为了满足以上约束条件，<strong>我们需要添加剪枝操作</strong>：在搜索过程中，若遇到值为 <span class="arithmatex">\(3\)</span> 的节点，则提前返回，停止继续搜索。</p>
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<div class="tabbed-set tabbed-alternate" data-tabs="4:11"><input checked="checked" id="__tabbed_4_1" name="__tabbed_4" type="radio" /><input id="__tabbed_4_2" name="__tabbed_4" type="radio" /><input id="__tabbed_4_3" name="__tabbed_4" type="radio" /><input id="__tabbed_4_4" name="__tabbed_4" type="radio" /><input id="__tabbed_4_5" name="__tabbed_4" type="radio" /><input id="__tabbed_4_6" name="__tabbed_4" type="radio" /><input id="__tabbed_4_7" name="__tabbed_4" type="radio" /><input id="__tabbed_4_8" name="__tabbed_4" type="radio" /><input id="__tabbed_4_9" name="__tabbed_4" type="radio" /><input id="__tabbed_4_10" name="__tabbed_4" type="radio" /><input id="__tabbed_4_11" name="__tabbed_4" type="radio" /><div class="tabbed-labels"><label for="__tabbed_4_1">Java</label><label for="__tabbed_4_2">C++</label><label for="__tabbed_4_3">Python</label><label for="__tabbed_4_4">Go</label><label for="__tabbed_4_5">JavaScript</label><label for="__tabbed_4_6">TypeScript</label><label for="__tabbed_4_7">C</label><label for="__tabbed_4_8">C#</label><label for="__tabbed_4_9">Swift</label><label for="__tabbed_4_10">Zig</label><label for="__tabbed_4_11">Dart</label></div>
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<div class="tabbed-content">
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<div class="tabbed-block">
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@ -3848,7 +3844,7 @@
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</code></pre></div>
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</div>
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<div class="tabbed-block">
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<div class="highlight"><span class="filename">preorder_traversal_iii_compact.py</span><pre><span></span><code><a id="__codelineno-24-1" name="__codelineno-24-1" href="#__codelineno-24-1"></a><span class="k">def</span> <span class="nf">pre_order</span><span class="p">(</span><span class="n">root</span><span class="p">:</span> <span class="n">TreeNode</span><span class="p">)</span> <span class="o">-></span> <span class="kc">None</span><span class="p">:</span>
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<div class="highlight"><span class="filename">preorder_traversal_iii_compact.py</span><pre><span></span><code><a id="__codelineno-24-1" name="__codelineno-24-1" href="#__codelineno-24-1"></a><span class="k">def</span> <span class="nf">pre_order</span><span class="p">(</span><span class="n">root</span><span class="p">:</span> <span class="n">TreeNode</span><span class="p">):</span>
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<a id="__codelineno-24-2" name="__codelineno-24-2" href="#__codelineno-24-2"></a><span class="w"> </span><span class="sd">"""前序遍历：例题三"""</span>
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<a id="__codelineno-24-3" name="__codelineno-24-3" href="#__codelineno-24-3"></a> <span class="c1"># 剪枝</span>
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<a id="__codelineno-24-4" name="__codelineno-24-4" href="#__codelineno-24-4"></a> <span class="k">if</span> <span class="n">root</span> <span class="ow">is</span> <span class="kc">None</span> <span class="ow">or</span> <span class="n">root</span><span class="o">.</span><span class="n">val</span> <span class="o">==</span> <span class="mi">3</span><span class="p">:</span>
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@ -3994,58 +3990,11 @@
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</div>
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</div>
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</div>
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<p>剪枝是一个非常形象的名词。在搜索过程中，<strong>我们利用约束条件“剪掉”了不满足约束条件的搜索分支</strong>，避免许多无意义的尝试，从而提升搜索效率。</p>
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||||
<p>剪枝是一个非常形象的名词。在搜索过程中，<strong>我们“剪掉”了不满足约束条件的搜索分支</strong>，避免许多无意义的尝试，从而实现搜索效率的提高。</p>
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<p><img alt="根据约束条件剪枝" src="../backtracking_algorithm.assets/preorder_find_constrained_paths.png" /></p>
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<p align="center"> Fig. 根据约束条件剪枝 </p>
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<h2 id="1313">13.1.3. 常用术语<a class="headerlink" href="#1313" title="Permanent link">¶</a></h2>
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<p>为了更清晰地分析算法问题，我们总结一下回溯算法中常用术语的含义，并对照例题三给出对应示例。</p>
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<table>
|
||||
<thead>
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||||
<tr>
|
||||
<th>名词</th>
|
||||
<th>定义</th>
|
||||
<th>例题三</th>
|
||||
</tr>
|
||||
</thead>
|
||||
<tbody>
|
||||
<tr>
|
||||
<td>解 Solution</td>
|
||||
<td>解是满足问题特定条件的答案，可能有一个或多个</td>
|
||||
<td>根节点到节点 <span class="arithmatex">\(7\)</span> 的满足约束条件的所有路径</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>约束条件 Constraint</td>
|
||||
<td>约束条件是问题中限制解的可行性的条件，通常用于剪枝</td>
|
||||
<td>路径中不包含节点 <span class="arithmatex">\(3\)</span> ，只包含一个节点 <span class="arithmatex">\(7\)</span></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>状态 State</td>
|
||||
<td>状态表示问题在某一时刻的情况，包括已经做出的选择</td>
|
||||
<td>当前已访问的节点路径，即 <code>path</code> 节点列表</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>尝试 Attempt</td>
|
||||
<td>尝试是根据可用选择来探索解空间的过程，包括做出选择，更新状态，检查是否为解</td>
|
||||
<td>递归访问左（右）子节点，将节点添加进 <code>path</code> ，判断节点的值是否为 <span class="arithmatex">\(7\)</span></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>回退 Backtracking</td>
|
||||
<td>回退指遇到不满足约束条件的状态时，撤销前面做出的选择，回到上一个状态</td>
|
||||
<td>当越过叶结点、结束结点访问、遇到值为 <span class="arithmatex">\(3\)</span> 的节点时终止搜索，函数返回</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>剪枝 Pruning</td>
|
||||
<td>剪枝是根据问题特性和约束条件避免无意义的搜索路径的方法，可提高搜索效率</td>
|
||||
<td>当遇到值为 <span class="arithmatex">\(3\)</span> 的节点时，则终止继续搜索</td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
<div class="admonition tip">
|
||||
<p class="admonition-title">Tip</p>
|
||||
<p>问题、解、状态等概念是通用的，在分治、回溯、动态规划、贪心等算法中都有涉及。</p>
|
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</div>
|
||||
<h2 id="1314">13.1.4. 框架代码<a class="headerlink" href="#1314" title="Permanent link">¶</a></h2>
|
||||
<h2 id="1313">13.1.3. 框架代码<a class="headerlink" href="#1313" title="Permanent link">¶</a></h2>
|
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<p>接下来，我们尝试将回溯的“尝试、回退、剪枝”的主体框架提炼出来，提升代码的通用性。</p>
|
||||
<p>在以下框架代码中，<code>state</code> 表示问题的当前状态，<code>choices</code> 表示当前状态下可以做出的选择。</p>
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<div class="tabbed-set tabbed-alternate" data-tabs="5:11"><input checked="checked" id="__tabbed_5_1" name="__tabbed_5" type="radio" /><input id="__tabbed_5_2" name="__tabbed_5" type="radio" /><input id="__tabbed_5_3" name="__tabbed_5" type="radio" /><input id="__tabbed_5_4" name="__tabbed_5" type="radio" /><input id="__tabbed_5_5" name="__tabbed_5" type="radio" /><input id="__tabbed_5_6" name="__tabbed_5" type="radio" /><input id="__tabbed_5_7" name="__tabbed_5" type="radio" /><input id="__tabbed_5_8" name="__tabbed_5" type="radio" /><input id="__tabbed_5_9" name="__tabbed_5" type="radio" /><input id="__tabbed_5_10" name="__tabbed_5" type="radio" /><input id="__tabbed_5_11" name="__tabbed_5" type="radio" /><div class="tabbed-labels"><label for="__tabbed_5_1">Java</label><label for="__tabbed_5_2">C++</label><label for="__tabbed_5_3">Python</label><label for="__tabbed_5_4">Go</label><label for="__tabbed_5_5">JavaScript</label><label for="__tabbed_5_6">TypeScript</label><label for="__tabbed_5_7">C</label><label for="__tabbed_5_8">C#</label><label for="__tabbed_5_9">Swift</label><label for="__tabbed_5_10">Zig</label><label for="__tabbed_5_11">Dart</label></div>
|
||||
@ -4057,20 +4006,21 @@
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<a id="__codelineno-33-4" name="__codelineno-33-4" href="#__codelineno-33-4"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isSolution</span><span class="p">(</span><span class="n">state</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-33-5" name="__codelineno-33-5" href="#__codelineno-33-5"></a><span class="w"> </span><span class="c1">// 记录解</span>
|
||||
<a id="__codelineno-33-6" name="__codelineno-33-6" href="#__codelineno-33-6"></a><span class="w"> </span><span class="n">recordSolution</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-33-7" name="__codelineno-33-7" href="#__codelineno-33-7"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-33-8" name="__codelineno-33-8" href="#__codelineno-33-8"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-33-9" name="__codelineno-33-9" href="#__codelineno-33-9"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-33-10" name="__codelineno-33-10" href="#__codelineno-33-10"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="n">Choice</span><span class="w"> </span><span class="n">choice</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-33-11" name="__codelineno-33-11" href="#__codelineno-33-11"></a><span class="w"> </span><span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-33-12" name="__codelineno-33-12" href="#__codelineno-33-12"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-33-13" name="__codelineno-33-13" href="#__codelineno-33-13"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-33-14" name="__codelineno-33-14" href="#__codelineno-33-14"></a><span class="w"> </span><span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-33-15" name="__codelineno-33-15" href="#__codelineno-33-15"></a><span class="w"> </span><span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choices</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-33-16" name="__codelineno-33-16" href="#__codelineno-33-16"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-33-17" name="__codelineno-33-17" href="#__codelineno-33-17"></a><span class="w"> </span><span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-33-18" name="__codelineno-33-18" href="#__codelineno-33-18"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-33-19" name="__codelineno-33-19" href="#__codelineno-33-19"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-33-20" name="__codelineno-33-20" href="#__codelineno-33-20"></a><span class="p">}</span>
|
||||
<a id="__codelineno-33-7" name="__codelineno-33-7" href="#__codelineno-33-7"></a><span class="w"> </span><span class="c1">// 停止继续搜索</span>
|
||||
<a id="__codelineno-33-8" name="__codelineno-33-8" href="#__codelineno-33-8"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-33-9" name="__codelineno-33-9" href="#__codelineno-33-9"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-33-10" name="__codelineno-33-10" href="#__codelineno-33-10"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-33-11" name="__codelineno-33-11" href="#__codelineno-33-11"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="n">Choice</span><span class="w"> </span><span class="n">choice</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-33-12" name="__codelineno-33-12" href="#__codelineno-33-12"></a><span class="w"> </span><span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-33-13" name="__codelineno-33-13" href="#__codelineno-33-13"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-33-14" name="__codelineno-33-14" href="#__codelineno-33-14"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-33-15" name="__codelineno-33-15" href="#__codelineno-33-15"></a><span class="w"> </span><span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-33-16" name="__codelineno-33-16" href="#__codelineno-33-16"></a><span class="w"> </span><span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choices</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-33-17" name="__codelineno-33-17" href="#__codelineno-33-17"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-33-18" name="__codelineno-33-18" href="#__codelineno-33-18"></a><span class="w"> </span><span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-33-19" name="__codelineno-33-19" href="#__codelineno-33-19"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-33-20" name="__codelineno-33-20" href="#__codelineno-33-20"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-33-21" name="__codelineno-33-21" href="#__codelineno-33-21"></a><span class="p">}</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
<div class="tabbed-block">
|
||||
@ -4080,39 +4030,41 @@
|
||||
<a id="__codelineno-34-4" name="__codelineno-34-4" href="#__codelineno-34-4"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isSolution</span><span class="p">(</span><span class="n">state</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-34-5" name="__codelineno-34-5" href="#__codelineno-34-5"></a><span class="w"> </span><span class="c1">// 记录解</span>
|
||||
<a id="__codelineno-34-6" name="__codelineno-34-6" href="#__codelineno-34-6"></a><span class="w"> </span><span class="n">recordSolution</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-34-7" name="__codelineno-34-7" href="#__codelineno-34-7"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-34-8" name="__codelineno-34-8" href="#__codelineno-34-8"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-34-9" name="__codelineno-34-9" href="#__codelineno-34-9"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-34-10" name="__codelineno-34-10" href="#__codelineno-34-10"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="n">Choice</span><span class="w"> </span><span class="n">choice</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-34-11" name="__codelineno-34-11" href="#__codelineno-34-11"></a><span class="w"> </span><span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-34-12" name="__codelineno-34-12" href="#__codelineno-34-12"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-34-13" name="__codelineno-34-13" href="#__codelineno-34-13"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-34-14" name="__codelineno-34-14" href="#__codelineno-34-14"></a><span class="w"> </span><span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-34-15" name="__codelineno-34-15" href="#__codelineno-34-15"></a><span class="w"> </span><span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choices</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-34-16" name="__codelineno-34-16" href="#__codelineno-34-16"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-34-17" name="__codelineno-34-17" href="#__codelineno-34-17"></a><span class="w"> </span><span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-34-18" name="__codelineno-34-18" href="#__codelineno-34-18"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-34-19" name="__codelineno-34-19" href="#__codelineno-34-19"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-34-20" name="__codelineno-34-20" href="#__codelineno-34-20"></a><span class="p">}</span>
|
||||
<a id="__codelineno-34-7" name="__codelineno-34-7" href="#__codelineno-34-7"></a><span class="w"> </span><span class="c1">// 停止继续搜索</span>
|
||||
<a id="__codelineno-34-8" name="__codelineno-34-8" href="#__codelineno-34-8"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-34-9" name="__codelineno-34-9" href="#__codelineno-34-9"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-34-10" name="__codelineno-34-10" href="#__codelineno-34-10"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-34-11" name="__codelineno-34-11" href="#__codelineno-34-11"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="n">Choice</span><span class="w"> </span><span class="n">choice</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-34-12" name="__codelineno-34-12" href="#__codelineno-34-12"></a><span class="w"> </span><span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-34-13" name="__codelineno-34-13" href="#__codelineno-34-13"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-34-14" name="__codelineno-34-14" href="#__codelineno-34-14"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-34-15" name="__codelineno-34-15" href="#__codelineno-34-15"></a><span class="w"> </span><span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-34-16" name="__codelineno-34-16" href="#__codelineno-34-16"></a><span class="w"> </span><span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choices</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-34-17" name="__codelineno-34-17" href="#__codelineno-34-17"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-34-18" name="__codelineno-34-18" href="#__codelineno-34-18"></a><span class="w"> </span><span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-34-19" name="__codelineno-34-19" href="#__codelineno-34-19"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-34-20" name="__codelineno-34-20" href="#__codelineno-34-20"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-34-21" name="__codelineno-34-21" href="#__codelineno-34-21"></a><span class="p">}</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
<div class="tabbed-block">
|
||||
<div class="highlight"><pre><span></span><code><a id="__codelineno-35-1" name="__codelineno-35-1" href="#__codelineno-35-1"></a><span class="k">def</span> <span class="nf">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="n">State</span><span class="p">,</span> <span class="n">choices</span><span class="p">:</span> <span class="nb">list</span><span class="p">[</span><span class="n">choice</span><span class="p">],</span> <span class="n">res</span><span class="p">:</span> <span class="nb">list</span><span class="p">[</span><span class="n">state</span><span class="p">])</span> <span class="o">-></span> <span class="kc">None</span><span class="p">:</span>
|
||||
<div class="highlight"><pre><span></span><code><a id="__codelineno-35-1" name="__codelineno-35-1" href="#__codelineno-35-1"></a><span class="k">def</span> <span class="nf">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="n">State</span><span class="p">,</span> <span class="n">choices</span><span class="p">:</span> <span class="nb">list</span><span class="p">[</span><span class="n">choice</span><span class="p">],</span> <span class="n">res</span><span class="p">:</span> <span class="nb">list</span><span class="p">[</span><span class="n">state</span><span class="p">]):</span>
|
||||
<a id="__codelineno-35-2" name="__codelineno-35-2" href="#__codelineno-35-2"></a><span class="w"> </span><span class="sd">"""回溯算法框架"""</span>
|
||||
<a id="__codelineno-35-3" name="__codelineno-35-3" href="#__codelineno-35-3"></a> <span class="c1"># 判断是否为解</span>
|
||||
<a id="__codelineno-35-4" name="__codelineno-35-4" href="#__codelineno-35-4"></a> <span class="k">if</span> <span class="n">is_solution</span><span class="p">(</span><span class="n">state</span><span class="p">):</span>
|
||||
<a id="__codelineno-35-5" name="__codelineno-35-5" href="#__codelineno-35-5"></a> <span class="c1"># 记录解</span>
|
||||
<a id="__codelineno-35-6" name="__codelineno-35-6" href="#__codelineno-35-6"></a> <span class="n">record_solution</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="n">res</span><span class="p">)</span>
|
||||
<a id="__codelineno-35-7" name="__codelineno-35-7" href="#__codelineno-35-7"></a> <span class="k">return</span>
|
||||
<a id="__codelineno-35-8" name="__codelineno-35-8" href="#__codelineno-35-8"></a> <span class="c1"># 遍历所有选择</span>
|
||||
<a id="__codelineno-35-9" name="__codelineno-35-9" href="#__codelineno-35-9"></a> <span class="k">for</span> <span class="n">choice</span> <span class="ow">in</span> <span class="n">choices</span><span class="p">:</span>
|
||||
<a id="__codelineno-35-10" name="__codelineno-35-10" href="#__codelineno-35-10"></a> <span class="c1"># 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-35-11" name="__codelineno-35-11" href="#__codelineno-35-11"></a> <span class="k">if</span> <span class="n">is_valid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">):</span>
|
||||
<a id="__codelineno-35-12" name="__codelineno-35-12" href="#__codelineno-35-12"></a> <span class="c1"># 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-35-13" name="__codelineno-35-13" href="#__codelineno-35-13"></a> <span class="n">make_choice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-35-14" name="__codelineno-35-14" href="#__codelineno-35-14"></a> <span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="n">choices</span><span class="p">,</span> <span class="n">res</span><span class="p">)</span>
|
||||
<a id="__codelineno-35-15" name="__codelineno-35-15" href="#__codelineno-35-15"></a> <span class="c1"># 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-35-16" name="__codelineno-35-16" href="#__codelineno-35-16"></a> <span class="n">undo_choice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-35-7" name="__codelineno-35-7" href="#__codelineno-35-7"></a> <span class="c1"># 停止继续搜索</span>
|
||||
<a id="__codelineno-35-8" name="__codelineno-35-8" href="#__codelineno-35-8"></a> <span class="k">return</span>
|
||||
<a id="__codelineno-35-9" name="__codelineno-35-9" href="#__codelineno-35-9"></a> <span class="c1"># 遍历所有选择</span>
|
||||
<a id="__codelineno-35-10" name="__codelineno-35-10" href="#__codelineno-35-10"></a> <span class="k">for</span> <span class="n">choice</span> <span class="ow">in</span> <span class="n">choices</span><span class="p">:</span>
|
||||
<a id="__codelineno-35-11" name="__codelineno-35-11" href="#__codelineno-35-11"></a> <span class="c1"># 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-35-12" name="__codelineno-35-12" href="#__codelineno-35-12"></a> <span class="k">if</span> <span class="n">is_valid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">):</span>
|
||||
<a id="__codelineno-35-13" name="__codelineno-35-13" href="#__codelineno-35-13"></a> <span class="c1"># 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-35-14" name="__codelineno-35-14" href="#__codelineno-35-14"></a> <span class="n">make_choice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-35-15" name="__codelineno-35-15" href="#__codelineno-35-15"></a> <span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="n">choices</span><span class="p">,</span> <span class="n">res</span><span class="p">)</span>
|
||||
<a id="__codelineno-35-16" name="__codelineno-35-16" href="#__codelineno-35-16"></a> <span class="c1"># 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-35-17" name="__codelineno-35-17" href="#__codelineno-35-17"></a> <span class="n">undo_choice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">)</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
<div class="tabbed-block">
|
||||
@ -4122,20 +4074,21 @@
|
||||
<a id="__codelineno-36-4" name="__codelineno-36-4" href="#__codelineno-36-4"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="nx">isSolution</span><span class="p">(</span><span class="nx">state</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-36-5" name="__codelineno-36-5" href="#__codelineno-36-5"></a><span class="w"> </span><span class="c1">// 记录解</span>
|
||||
<a id="__codelineno-36-6" name="__codelineno-36-6" href="#__codelineno-36-6"></a><span class="w"> </span><span class="nx">recordSolution</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">res</span><span class="p">)</span>
|
||||
<a id="__codelineno-36-7" name="__codelineno-36-7" href="#__codelineno-36-7"></a><span class="w"> </span><span class="k">return</span>
|
||||
<a id="__codelineno-36-8" name="__codelineno-36-8" href="#__codelineno-36-8"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-36-9" name="__codelineno-36-9" href="#__codelineno-36-9"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-36-10" name="__codelineno-36-10" href="#__codelineno-36-10"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="nx">_</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="k">range</span><span class="w"> </span><span class="nx">choices</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-36-11" name="__codelineno-36-11" href="#__codelineno-36-11"></a><span class="w"> </span><span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-36-12" name="__codelineno-36-12" href="#__codelineno-36-12"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="nx">isValid</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-36-13" name="__codelineno-36-13" href="#__codelineno-36-13"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-36-14" name="__codelineno-36-14" href="#__codelineno-36-14"></a><span class="w"> </span><span class="nx">makeChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-36-15" name="__codelineno-36-15" href="#__codelineno-36-15"></a><span class="w"> </span><span class="nx">backtrack</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choices</span><span class="p">,</span><span class="w"> </span><span class="nx">res</span><span class="p">)</span>
|
||||
<a id="__codelineno-36-16" name="__codelineno-36-16" href="#__codelineno-36-16"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-36-17" name="__codelineno-36-17" href="#__codelineno-36-17"></a><span class="w"> </span><span class="nx">undoChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-36-18" name="__codelineno-36-18" href="#__codelineno-36-18"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-36-19" name="__codelineno-36-19" href="#__codelineno-36-19"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-36-20" name="__codelineno-36-20" href="#__codelineno-36-20"></a><span class="p">}</span>
|
||||
<a id="__codelineno-36-7" name="__codelineno-36-7" href="#__codelineno-36-7"></a><span class="w"> </span><span class="c1">// 停止继续搜索</span>
|
||||
<a id="__codelineno-36-8" name="__codelineno-36-8" href="#__codelineno-36-8"></a><span class="w"> </span><span class="k">return</span>
|
||||
<a id="__codelineno-36-9" name="__codelineno-36-9" href="#__codelineno-36-9"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-36-10" name="__codelineno-36-10" href="#__codelineno-36-10"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-36-11" name="__codelineno-36-11" href="#__codelineno-36-11"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="nx">_</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="k">range</span><span class="w"> </span><span class="nx">choices</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-36-12" name="__codelineno-36-12" href="#__codelineno-36-12"></a><span class="w"> </span><span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-36-13" name="__codelineno-36-13" href="#__codelineno-36-13"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="nx">isValid</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-36-14" name="__codelineno-36-14" href="#__codelineno-36-14"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-36-15" name="__codelineno-36-15" href="#__codelineno-36-15"></a><span class="w"> </span><span class="nx">makeChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-36-16" name="__codelineno-36-16" href="#__codelineno-36-16"></a><span class="w"> </span><span class="nx">backtrack</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choices</span><span class="p">,</span><span class="w"> </span><span class="nx">res</span><span class="p">)</span>
|
||||
<a id="__codelineno-36-17" name="__codelineno-36-17" href="#__codelineno-36-17"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-36-18" name="__codelineno-36-18" href="#__codelineno-36-18"></a><span class="w"> </span><span class="nx">undoChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-36-19" name="__codelineno-36-19" href="#__codelineno-36-19"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-36-20" name="__codelineno-36-20" href="#__codelineno-36-20"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-36-21" name="__codelineno-36-21" href="#__codelineno-36-21"></a><span class="p">}</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
<div class="tabbed-block">
|
||||
@ -4145,20 +4098,21 @@
|
||||
<a id="__codelineno-37-4" name="__codelineno-37-4" href="#__codelineno-37-4"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="nx">isSolution</span><span class="p">(</span><span class="nx">state</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-37-5" name="__codelineno-37-5" href="#__codelineno-37-5"></a><span class="w"> </span><span class="c1">// 记录解</span>
|
||||
<a id="__codelineno-37-6" name="__codelineno-37-6" href="#__codelineno-37-6"></a><span class="w"> </span><span class="nx">recordSolution</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-37-7" name="__codelineno-37-7" href="#__codelineno-37-7"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-37-8" name="__codelineno-37-8" href="#__codelineno-37-8"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-37-9" name="__codelineno-37-9" href="#__codelineno-37-9"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-37-10" name="__codelineno-37-10" href="#__codelineno-37-10"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kd">let</span><span class="w"> </span><span class="nx">choice</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="nx">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-37-11" name="__codelineno-37-11" href="#__codelineno-37-11"></a><span class="w"> </span><span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-37-12" name="__codelineno-37-12" href="#__codelineno-37-12"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="nx">isValid</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-37-13" name="__codelineno-37-13" href="#__codelineno-37-13"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-37-14" name="__codelineno-37-14" href="#__codelineno-37-14"></a><span class="w"> </span><span class="nx">makeChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-37-15" name="__codelineno-37-15" href="#__codelineno-37-15"></a><span class="w"> </span><span class="nx">backtrack</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choices</span><span class="p">,</span><span class="w"> </span><span class="nx">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-37-16" name="__codelineno-37-16" href="#__codelineno-37-16"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-37-17" name="__codelineno-37-17" href="#__codelineno-37-17"></a><span class="w"> </span><span class="nx">undoChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-37-18" name="__codelineno-37-18" href="#__codelineno-37-18"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-37-19" name="__codelineno-37-19" href="#__codelineno-37-19"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-37-20" name="__codelineno-37-20" href="#__codelineno-37-20"></a><span class="p">}</span>
|
||||
<a id="__codelineno-37-7" name="__codelineno-37-7" href="#__codelineno-37-7"></a><span class="w"> </span><span class="c1">// 停止继续搜索</span>
|
||||
<a id="__codelineno-37-8" name="__codelineno-37-8" href="#__codelineno-37-8"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-37-9" name="__codelineno-37-9" href="#__codelineno-37-9"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-37-10" name="__codelineno-37-10" href="#__codelineno-37-10"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-37-11" name="__codelineno-37-11" href="#__codelineno-37-11"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kd">let</span><span class="w"> </span><span class="nx">choice</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="nx">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-37-12" name="__codelineno-37-12" href="#__codelineno-37-12"></a><span class="w"> </span><span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-37-13" name="__codelineno-37-13" href="#__codelineno-37-13"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="nx">isValid</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-37-14" name="__codelineno-37-14" href="#__codelineno-37-14"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-37-15" name="__codelineno-37-15" href="#__codelineno-37-15"></a><span class="w"> </span><span class="nx">makeChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-37-16" name="__codelineno-37-16" href="#__codelineno-37-16"></a><span class="w"> </span><span class="nx">backtrack</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choices</span><span class="p">,</span><span class="w"> </span><span class="nx">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-37-17" name="__codelineno-37-17" href="#__codelineno-37-17"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-37-18" name="__codelineno-37-18" href="#__codelineno-37-18"></a><span class="w"> </span><span class="nx">undoChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-37-19" name="__codelineno-37-19" href="#__codelineno-37-19"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-37-20" name="__codelineno-37-20" href="#__codelineno-37-20"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-37-21" name="__codelineno-37-21" href="#__codelineno-37-21"></a><span class="p">}</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
<div class="tabbed-block">
|
||||
@ -4168,20 +4122,21 @@
|
||||
<a id="__codelineno-38-4" name="__codelineno-38-4" href="#__codelineno-38-4"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="nx">isSolution</span><span class="p">(</span><span class="nx">state</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-38-5" name="__codelineno-38-5" href="#__codelineno-38-5"></a><span class="w"> </span><span class="c1">// 记录解</span>
|
||||
<a id="__codelineno-38-6" name="__codelineno-38-6" href="#__codelineno-38-6"></a><span class="w"> </span><span class="nx">recordSolution</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-38-7" name="__codelineno-38-7" href="#__codelineno-38-7"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-38-8" name="__codelineno-38-8" href="#__codelineno-38-8"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-38-9" name="__codelineno-38-9" href="#__codelineno-38-9"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-38-10" name="__codelineno-38-10" href="#__codelineno-38-10"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kd">let</span><span class="w"> </span><span class="nx">choice</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="nx">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-38-11" name="__codelineno-38-11" href="#__codelineno-38-11"></a><span class="w"> </span><span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-38-12" name="__codelineno-38-12" href="#__codelineno-38-12"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="nx">isValid</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-38-13" name="__codelineno-38-13" href="#__codelineno-38-13"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-38-14" name="__codelineno-38-14" href="#__codelineno-38-14"></a><span class="w"> </span><span class="nx">makeChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-38-15" name="__codelineno-38-15" href="#__codelineno-38-15"></a><span class="w"> </span><span class="nx">backtrack</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choices</span><span class="p">,</span><span class="w"> </span><span class="nx">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-38-16" name="__codelineno-38-16" href="#__codelineno-38-16"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-38-17" name="__codelineno-38-17" href="#__codelineno-38-17"></a><span class="w"> </span><span class="nx">undoChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-38-18" name="__codelineno-38-18" href="#__codelineno-38-18"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-38-19" name="__codelineno-38-19" href="#__codelineno-38-19"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-38-20" name="__codelineno-38-20" href="#__codelineno-38-20"></a><span class="p">}</span>
|
||||
<a id="__codelineno-38-7" name="__codelineno-38-7" href="#__codelineno-38-7"></a><span class="w"> </span><span class="c1">// 停止继续搜索</span>
|
||||
<a id="__codelineno-38-8" name="__codelineno-38-8" href="#__codelineno-38-8"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-38-9" name="__codelineno-38-9" href="#__codelineno-38-9"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-38-10" name="__codelineno-38-10" href="#__codelineno-38-10"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-38-11" name="__codelineno-38-11" href="#__codelineno-38-11"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kd">let</span><span class="w"> </span><span class="nx">choice</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="nx">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-38-12" name="__codelineno-38-12" href="#__codelineno-38-12"></a><span class="w"> </span><span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-38-13" name="__codelineno-38-13" href="#__codelineno-38-13"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="nx">isValid</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-38-14" name="__codelineno-38-14" href="#__codelineno-38-14"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-38-15" name="__codelineno-38-15" href="#__codelineno-38-15"></a><span class="w"> </span><span class="nx">makeChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-38-16" name="__codelineno-38-16" href="#__codelineno-38-16"></a><span class="w"> </span><span class="nx">backtrack</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choices</span><span class="p">,</span><span class="w"> </span><span class="nx">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-38-17" name="__codelineno-38-17" href="#__codelineno-38-17"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-38-18" name="__codelineno-38-18" href="#__codelineno-38-18"></a><span class="w"> </span><span class="nx">undoChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-38-19" name="__codelineno-38-19" href="#__codelineno-38-19"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-38-20" name="__codelineno-38-20" href="#__codelineno-38-20"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-38-21" name="__codelineno-38-21" href="#__codelineno-38-21"></a><span class="p">}</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
<div class="tabbed-block">
|
||||
@ -4191,20 +4146,21 @@
|
||||
<a id="__codelineno-39-4" name="__codelineno-39-4" href="#__codelineno-39-4"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isSolution</span><span class="p">(</span><span class="n">state</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-39-5" name="__codelineno-39-5" href="#__codelineno-39-5"></a><span class="w"> </span><span class="c1">// 记录解</span>
|
||||
<a id="__codelineno-39-6" name="__codelineno-39-6" href="#__codelineno-39-6"></a><span class="w"> </span><span class="n">recordSolution</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">,</span><span class="w"> </span><span class="n">numRes</span><span class="p">);</span>
|
||||
<a id="__codelineno-39-7" name="__codelineno-39-7" href="#__codelineno-39-7"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-39-8" name="__codelineno-39-8" href="#__codelineno-39-8"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-39-9" name="__codelineno-39-9" href="#__codelineno-39-9"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-39-10" name="__codelineno-39-10" href="#__codelineno-39-10"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kt">int</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="n">numChoices</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="o">++</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-39-11" name="__codelineno-39-11" href="#__codelineno-39-11"></a><span class="w"> </span><span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-39-12" name="__codelineno-39-12" href="#__codelineno-39-12"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">choices</span><span class="p">[</span><span class="n">i</span><span class="p">]))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-39-13" name="__codelineno-39-13" href="#__codelineno-39-13"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-39-14" name="__codelineno-39-14" href="#__codelineno-39-14"></a><span class="w"> </span><span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">choices</span><span class="p">[</span><span class="n">i</span><span class="p">]);</span>
|
||||
<a id="__codelineno-39-15" name="__codelineno-39-15" href="#__codelineno-39-15"></a><span class="w"> </span><span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choices</span><span class="p">,</span><span class="w"> </span><span class="n">numChoices</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">,</span><span class="w"> </span><span class="n">numRes</span><span class="p">);</span>
|
||||
<a id="__codelineno-39-16" name="__codelineno-39-16" href="#__codelineno-39-16"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-39-17" name="__codelineno-39-17" href="#__codelineno-39-17"></a><span class="w"> </span><span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">choices</span><span class="p">[</span><span class="n">i</span><span class="p">]);</span>
|
||||
<a id="__codelineno-39-18" name="__codelineno-39-18" href="#__codelineno-39-18"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-39-19" name="__codelineno-39-19" href="#__codelineno-39-19"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-39-20" name="__codelineno-39-20" href="#__codelineno-39-20"></a><span class="p">}</span>
|
||||
<a id="__codelineno-39-7" name="__codelineno-39-7" href="#__codelineno-39-7"></a><span class="w"> </span><span class="c1">// 停止继续搜索</span>
|
||||
<a id="__codelineno-39-8" name="__codelineno-39-8" href="#__codelineno-39-8"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-39-9" name="__codelineno-39-9" href="#__codelineno-39-9"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-39-10" name="__codelineno-39-10" href="#__codelineno-39-10"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-39-11" name="__codelineno-39-11" href="#__codelineno-39-11"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kt">int</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="n">numChoices</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="o">++</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-39-12" name="__codelineno-39-12" href="#__codelineno-39-12"></a><span class="w"> </span><span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-39-13" name="__codelineno-39-13" href="#__codelineno-39-13"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">choices</span><span class="p">[</span><span class="n">i</span><span class="p">]))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-39-14" name="__codelineno-39-14" href="#__codelineno-39-14"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-39-15" name="__codelineno-39-15" href="#__codelineno-39-15"></a><span class="w"> </span><span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">choices</span><span class="p">[</span><span class="n">i</span><span class="p">]);</span>
|
||||
<a id="__codelineno-39-16" name="__codelineno-39-16" href="#__codelineno-39-16"></a><span class="w"> </span><span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choices</span><span class="p">,</span><span class="w"> </span><span class="n">numChoices</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">,</span><span class="w"> </span><span class="n">numRes</span><span class="p">);</span>
|
||||
<a id="__codelineno-39-17" name="__codelineno-39-17" href="#__codelineno-39-17"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-39-18" name="__codelineno-39-18" href="#__codelineno-39-18"></a><span class="w"> </span><span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">choices</span><span class="p">[</span><span class="n">i</span><span class="p">]);</span>
|
||||
<a id="__codelineno-39-19" name="__codelineno-39-19" href="#__codelineno-39-19"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-39-20" name="__codelineno-39-20" href="#__codelineno-39-20"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-39-21" name="__codelineno-39-21" href="#__codelineno-39-21"></a><span class="p">}</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
<div class="tabbed-block">
|
||||
@ -4214,20 +4170,21 @@
|
||||
<a id="__codelineno-40-4" name="__codelineno-40-4" href="#__codelineno-40-4"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isSolution</span><span class="p">(</span><span class="n">state</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-40-5" name="__codelineno-40-5" href="#__codelineno-40-5"></a><span class="w"> </span><span class="c1">// 记录解</span>
|
||||
<a id="__codelineno-40-6" name="__codelineno-40-6" href="#__codelineno-40-6"></a><span class="w"> </span><span class="n">recordSolution</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-40-7" name="__codelineno-40-7" href="#__codelineno-40-7"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-40-8" name="__codelineno-40-8" href="#__codelineno-40-8"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-40-9" name="__codelineno-40-9" href="#__codelineno-40-9"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-40-10" name="__codelineno-40-10" href="#__codelineno-40-10"></a><span class="w"> </span><span class="k">foreach</span><span class="w"> </span><span class="p">(</span><span class="n">Choice</span><span class="w"> </span><span class="n">choice</span><span class="w"> </span><span class="k">in</span><span class="w"> </span><span class="n">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-40-11" name="__codelineno-40-11" href="#__codelineno-40-11"></a><span class="w"> </span><span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-40-12" name="__codelineno-40-12" href="#__codelineno-40-12"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-40-13" name="__codelineno-40-13" href="#__codelineno-40-13"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-40-14" name="__codelineno-40-14" href="#__codelineno-40-14"></a><span class="w"> </span><span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-40-15" name="__codelineno-40-15" href="#__codelineno-40-15"></a><span class="w"> </span><span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choices</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-40-16" name="__codelineno-40-16" href="#__codelineno-40-16"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-40-17" name="__codelineno-40-17" href="#__codelineno-40-17"></a><span class="w"> </span><span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-40-18" name="__codelineno-40-18" href="#__codelineno-40-18"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-40-19" name="__codelineno-40-19" href="#__codelineno-40-19"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-40-20" name="__codelineno-40-20" href="#__codelineno-40-20"></a><span class="p">}</span>
|
||||
<a id="__codelineno-40-7" name="__codelineno-40-7" href="#__codelineno-40-7"></a><span class="w"> </span><span class="c1">// 停止继续搜索</span>
|
||||
<a id="__codelineno-40-8" name="__codelineno-40-8" href="#__codelineno-40-8"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-40-9" name="__codelineno-40-9" href="#__codelineno-40-9"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-40-10" name="__codelineno-40-10" href="#__codelineno-40-10"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-40-11" name="__codelineno-40-11" href="#__codelineno-40-11"></a><span class="w"> </span><span class="k">foreach</span><span class="w"> </span><span class="p">(</span><span class="n">Choice</span><span class="w"> </span><span class="n">choice</span><span class="w"> </span><span class="k">in</span><span class="w"> </span><span class="n">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-40-12" name="__codelineno-40-12" href="#__codelineno-40-12"></a><span class="w"> </span><span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-40-13" name="__codelineno-40-13" href="#__codelineno-40-13"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-40-14" name="__codelineno-40-14" href="#__codelineno-40-14"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-40-15" name="__codelineno-40-15" href="#__codelineno-40-15"></a><span class="w"> </span><span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-40-16" name="__codelineno-40-16" href="#__codelineno-40-16"></a><span class="w"> </span><span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choices</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-40-17" name="__codelineno-40-17" href="#__codelineno-40-17"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-40-18" name="__codelineno-40-18" href="#__codelineno-40-18"></a><span class="w"> </span><span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-40-19" name="__codelineno-40-19" href="#__codelineno-40-19"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-40-20" name="__codelineno-40-20" href="#__codelineno-40-20"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-40-21" name="__codelineno-40-21" href="#__codelineno-40-21"></a><span class="p">}</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
<div class="tabbed-block">
|
||||
@ -4237,20 +4194,21 @@
|
||||
<a id="__codelineno-41-4" name="__codelineno-41-4" href="#__codelineno-41-4"></a> <span class="k">if</span> <span class="n">isSolution</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="n">state</span><span class="p">)</span> <span class="p">{</span>
|
||||
<a id="__codelineno-41-5" name="__codelineno-41-5" href="#__codelineno-41-5"></a> <span class="c1">// 记录解</span>
|
||||
<a id="__codelineno-41-6" name="__codelineno-41-6" href="#__codelineno-41-6"></a> <span class="n">recordSolution</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="n">state</span><span class="p">,</span> <span class="n">res</span><span class="p">:</span> <span class="p">&</span><span class="n">res</span><span class="p">)</span>
|
||||
<a id="__codelineno-41-7" name="__codelineno-41-7" href="#__codelineno-41-7"></a> <span class="k">return</span>
|
||||
<a id="__codelineno-41-8" name="__codelineno-41-8" href="#__codelineno-41-8"></a> <span class="p">}</span>
|
||||
<a id="__codelineno-41-9" name="__codelineno-41-9" href="#__codelineno-41-9"></a> <span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-41-10" name="__codelineno-41-10" href="#__codelineno-41-10"></a> <span class="k">for</span> <span class="n">choice</span> <span class="k">in</span> <span class="n">choices</span> <span class="p">{</span>
|
||||
<a id="__codelineno-41-11" name="__codelineno-41-11" href="#__codelineno-41-11"></a> <span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-41-12" name="__codelineno-41-12" href="#__codelineno-41-12"></a> <span class="k">if</span> <span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">:</span> <span class="n">choice</span><span class="p">)</span> <span class="p">{</span>
|
||||
<a id="__codelineno-41-13" name="__codelineno-41-13" href="#__codelineno-41-13"></a> <span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-41-14" name="__codelineno-41-14" href="#__codelineno-41-14"></a> <span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="p">&</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">:</span> <span class="n">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-41-15" name="__codelineno-41-15" href="#__codelineno-41-15"></a> <span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="p">&</span><span class="n">state</span><span class="p">,</span> <span class="n">choices</span><span class="p">:</span> <span class="n">choices</span><span class="p">,</span> <span class="n">res</span><span class="p">:</span> <span class="p">&</span><span class="n">res</span><span class="p">)</span>
|
||||
<a id="__codelineno-41-16" name="__codelineno-41-16" href="#__codelineno-41-16"></a> <span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-41-17" name="__codelineno-41-17" href="#__codelineno-41-17"></a> <span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="p">&</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">:</span> <span class="n">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-41-18" name="__codelineno-41-18" href="#__codelineno-41-18"></a> <span class="p">}</span>
|
||||
<a id="__codelineno-41-19" name="__codelineno-41-19" href="#__codelineno-41-19"></a> <span class="p">}</span>
|
||||
<a id="__codelineno-41-20" name="__codelineno-41-20" href="#__codelineno-41-20"></a><span class="p">}</span>
|
||||
<a id="__codelineno-41-7" name="__codelineno-41-7" href="#__codelineno-41-7"></a> <span class="c1">// 停止继续搜索</span>
|
||||
<a id="__codelineno-41-8" name="__codelineno-41-8" href="#__codelineno-41-8"></a> <span class="k">return</span>
|
||||
<a id="__codelineno-41-9" name="__codelineno-41-9" href="#__codelineno-41-9"></a> <span class="p">}</span>
|
||||
<a id="__codelineno-41-10" name="__codelineno-41-10" href="#__codelineno-41-10"></a> <span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-41-11" name="__codelineno-41-11" href="#__codelineno-41-11"></a> <span class="k">for</span> <span class="n">choice</span> <span class="k">in</span> <span class="n">choices</span> <span class="p">{</span>
|
||||
<a id="__codelineno-41-12" name="__codelineno-41-12" href="#__codelineno-41-12"></a> <span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-41-13" name="__codelineno-41-13" href="#__codelineno-41-13"></a> <span class="k">if</span> <span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">:</span> <span class="n">choice</span><span class="p">)</span> <span class="p">{</span>
|
||||
<a id="__codelineno-41-14" name="__codelineno-41-14" href="#__codelineno-41-14"></a> <span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-41-15" name="__codelineno-41-15" href="#__codelineno-41-15"></a> <span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="p">&</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">:</span> <span class="n">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-41-16" name="__codelineno-41-16" href="#__codelineno-41-16"></a> <span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="p">&</span><span class="n">state</span><span class="p">,</span> <span class="n">choices</span><span class="p">:</span> <span class="n">choices</span><span class="p">,</span> <span class="n">res</span><span class="p">:</span> <span class="p">&</span><span class="n">res</span><span class="p">)</span>
|
||||
<a id="__codelineno-41-17" name="__codelineno-41-17" href="#__codelineno-41-17"></a> <span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-41-18" name="__codelineno-41-18" href="#__codelineno-41-18"></a> <span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="p">&</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">:</span> <span class="n">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-41-19" name="__codelineno-41-19" href="#__codelineno-41-19"></a> <span class="p">}</span>
|
||||
<a id="__codelineno-41-20" name="__codelineno-41-20" href="#__codelineno-41-20"></a> <span class="p">}</span>
|
||||
<a id="__codelineno-41-21" name="__codelineno-41-21" href="#__codelineno-41-21"></a><span class="p">}</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
<div class="tabbed-block">
|
||||
@ -4264,25 +4222,26 @@
|
||||
<a id="__codelineno-43-4" name="__codelineno-43-4" href="#__codelineno-43-4"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isSolution</span><span class="p">(</span><span class="n">state</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-43-5" name="__codelineno-43-5" href="#__codelineno-43-5"></a><span class="w"> </span><span class="c1">// 记录解</span>
|
||||
<a id="__codelineno-43-6" name="__codelineno-43-6" href="#__codelineno-43-6"></a><span class="w"> </span><span class="n">recordSolution</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-43-7" name="__codelineno-43-7" href="#__codelineno-43-7"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-43-8" name="__codelineno-43-8" href="#__codelineno-43-8"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-43-9" name="__codelineno-43-9" href="#__codelineno-43-9"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-43-10" name="__codelineno-43-10" href="#__codelineno-43-10"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="n">Choice</span><span class="w"> </span><span class="n">choice</span><span class="w"> </span><span class="k">in</span><span class="w"> </span><span class="n">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-43-11" name="__codelineno-43-11" href="#__codelineno-43-11"></a><span class="w"> </span><span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-43-12" name="__codelineno-43-12" href="#__codelineno-43-12"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-43-13" name="__codelineno-43-13" href="#__codelineno-43-13"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-43-14" name="__codelineno-43-14" href="#__codelineno-43-14"></a><span class="w"> </span><span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-43-15" name="__codelineno-43-15" href="#__codelineno-43-15"></a><span class="w"> </span><span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choices</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-43-16" name="__codelineno-43-16" href="#__codelineno-43-16"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-43-17" name="__codelineno-43-17" href="#__codelineno-43-17"></a><span class="w"> </span><span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-43-18" name="__codelineno-43-18" href="#__codelineno-43-18"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-43-19" name="__codelineno-43-19" href="#__codelineno-43-19"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-43-20" name="__codelineno-43-20" href="#__codelineno-43-20"></a><span class="p">}</span>
|
||||
<a id="__codelineno-43-7" name="__codelineno-43-7" href="#__codelineno-43-7"></a><span class="w"> </span><span class="c1">// 停止继续搜索</span>
|
||||
<a id="__codelineno-43-8" name="__codelineno-43-8" href="#__codelineno-43-8"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-43-9" name="__codelineno-43-9" href="#__codelineno-43-9"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-43-10" name="__codelineno-43-10" href="#__codelineno-43-10"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-43-11" name="__codelineno-43-11" href="#__codelineno-43-11"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="n">Choice</span><span class="w"> </span><span class="n">choice</span><span class="w"> </span><span class="k">in</span><span class="w"> </span><span class="n">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-43-12" name="__codelineno-43-12" href="#__codelineno-43-12"></a><span class="w"> </span><span class="c1">// 剪枝：判断选择是否合法</span>
|
||||
<a id="__codelineno-43-13" name="__codelineno-43-13" href="#__codelineno-43-13"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-43-14" name="__codelineno-43-14" href="#__codelineno-43-14"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-43-15" name="__codelineno-43-15" href="#__codelineno-43-15"></a><span class="w"> </span><span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-43-16" name="__codelineno-43-16" href="#__codelineno-43-16"></a><span class="w"> </span><span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choices</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-43-17" name="__codelineno-43-17" href="#__codelineno-43-17"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-43-18" name="__codelineno-43-18" href="#__codelineno-43-18"></a><span class="w"> </span><span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-43-19" name="__codelineno-43-19" href="#__codelineno-43-19"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-43-20" name="__codelineno-43-20" href="#__codelineno-43-20"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-43-21" name="__codelineno-43-21" href="#__codelineno-43-21"></a><span class="p">}</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>下面，我们基于框架代码来解决例题三：状态 <code>state</code> 为节点遍历路径，选择 <code>choices</code> 为当前节点的左子节点和右子节点，结果 <code>res</code> 是路径列表。</p>
|
||||
<p>接下来，我们基于框架代码来解决例题三。状态 <code>state</code> 为节点遍历路径，选择 <code>choices</code> 为当前节点的左子节点和右子节点，结果 <code>res</code> 是路径列表。</p>
|
||||
<div class="tabbed-set tabbed-alternate" data-tabs="6:11"><input checked="checked" id="__tabbed_6_1" name="__tabbed_6" type="radio" /><input id="__tabbed_6_2" name="__tabbed_6" type="radio" /><input id="__tabbed_6_3" name="__tabbed_6" type="radio" /><input id="__tabbed_6_4" name="__tabbed_6" type="radio" /><input id="__tabbed_6_5" name="__tabbed_6" type="radio" /><input id="__tabbed_6_6" name="__tabbed_6" type="radio" /><input id="__tabbed_6_7" name="__tabbed_6" type="radio" /><input id="__tabbed_6_8" name="__tabbed_6" type="radio" /><input id="__tabbed_6_9" name="__tabbed_6" type="radio" /><input id="__tabbed_6_10" name="__tabbed_6" type="radio" /><input id="__tabbed_6_11" name="__tabbed_6" type="radio" /><div class="tabbed-labels"><label for="__tabbed_6_1">Java</label><label for="__tabbed_6_2">C++</label><label for="__tabbed_6_3">Python</label><label for="__tabbed_6_4">Go</label><label for="__tabbed_6_5">JavaScript</label><label for="__tabbed_6_6">TypeScript</label><label for="__tabbed_6_7">C</label><label for="__tabbed_6_8">C#</label><label for="__tabbed_6_9">Swift</label><label for="__tabbed_6_10">Zig</label><label for="__tabbed_6_11">Dart</label></div>
|
||||
<div class="tabbed-content">
|
||||
<div class="tabbed-block">
|
||||
@ -4317,21 +4276,20 @@
|
||||
<a id="__codelineno-44-29" name="__codelineno-44-29" href="#__codelineno-44-29"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isSolution</span><span class="p">(</span><span class="n">state</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-44-30" name="__codelineno-44-30" href="#__codelineno-44-30"></a><span class="w"> </span><span class="c1">// 记录解</span>
|
||||
<a id="__codelineno-44-31" name="__codelineno-44-31" href="#__codelineno-44-31"></a><span class="w"> </span><span class="n">recordSolution</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-44-32" name="__codelineno-44-32" href="#__codelineno-44-32"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-44-33" name="__codelineno-44-33" href="#__codelineno-44-33"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-44-34" name="__codelineno-44-34" href="#__codelineno-44-34"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-44-35" name="__codelineno-44-35" href="#__codelineno-44-35"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="n">TreeNode</span><span class="w"> </span><span class="n">choice</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-44-36" name="__codelineno-44-36" href="#__codelineno-44-36"></a><span class="w"> </span><span class="c1">// 剪枝：检查选择是否合法</span>
|
||||
<a id="__codelineno-44-37" name="__codelineno-44-37" href="#__codelineno-44-37"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-44-38" name="__codelineno-44-38" href="#__codelineno-44-38"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-44-39" name="__codelineno-44-39" href="#__codelineno-44-39"></a><span class="w"> </span><span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-44-40" name="__codelineno-44-40" href="#__codelineno-44-40"></a><span class="w"> </span><span class="c1">// 进行下一轮选择</span>
|
||||
<a id="__codelineno-44-41" name="__codelineno-44-41" href="#__codelineno-44-41"></a><span class="w"> </span><span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">Arrays</span><span class="p">.</span><span class="na">asList</span><span class="p">(</span><span class="n">choice</span><span class="p">.</span><span class="na">left</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">.</span><span class="na">right</span><span class="p">),</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-44-42" name="__codelineno-44-42" href="#__codelineno-44-42"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-44-43" name="__codelineno-44-43" href="#__codelineno-44-43"></a><span class="w"> </span><span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-44-44" name="__codelineno-44-44" href="#__codelineno-44-44"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-44-45" name="__codelineno-44-45" href="#__codelineno-44-45"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-44-46" name="__codelineno-44-46" href="#__codelineno-44-46"></a><span class="p">}</span>
|
||||
<a id="__codelineno-44-32" name="__codelineno-44-32" href="#__codelineno-44-32"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-44-33" name="__codelineno-44-33" href="#__codelineno-44-33"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-44-34" name="__codelineno-44-34" href="#__codelineno-44-34"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="n">TreeNode</span><span class="w"> </span><span class="n">choice</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-44-35" name="__codelineno-44-35" href="#__codelineno-44-35"></a><span class="w"> </span><span class="c1">// 剪枝：检查选择是否合法</span>
|
||||
<a id="__codelineno-44-36" name="__codelineno-44-36" href="#__codelineno-44-36"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-44-37" name="__codelineno-44-37" href="#__codelineno-44-37"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-44-38" name="__codelineno-44-38" href="#__codelineno-44-38"></a><span class="w"> </span><span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-44-39" name="__codelineno-44-39" href="#__codelineno-44-39"></a><span class="w"> </span><span class="c1">// 进行下一轮选择</span>
|
||||
<a id="__codelineno-44-40" name="__codelineno-44-40" href="#__codelineno-44-40"></a><span class="w"> </span><span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">Arrays</span><span class="p">.</span><span class="na">asList</span><span class="p">(</span><span class="n">choice</span><span class="p">.</span><span class="na">left</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">.</span><span class="na">right</span><span class="p">),</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-44-41" name="__codelineno-44-41" href="#__codelineno-44-41"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-44-42" name="__codelineno-44-42" href="#__codelineno-44-42"></a><span class="w"> </span><span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-44-43" name="__codelineno-44-43" href="#__codelineno-44-43"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-44-44" name="__codelineno-44-44" href="#__codelineno-44-44"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-44-45" name="__codelineno-44-45" href="#__codelineno-44-45"></a><span class="p">}</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
<div class="tabbed-block">
|
||||
@ -4366,22 +4324,21 @@
|
||||
<a id="__codelineno-45-29" name="__codelineno-45-29" href="#__codelineno-45-29"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isSolution</span><span class="p">(</span><span class="n">state</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-45-30" name="__codelineno-45-30" href="#__codelineno-45-30"></a><span class="w"> </span><span class="c1">// 记录解</span>
|
||||
<a id="__codelineno-45-31" name="__codelineno-45-31" href="#__codelineno-45-31"></a><span class="w"> </span><span class="n">recordSolution</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-45-32" name="__codelineno-45-32" href="#__codelineno-45-32"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-45-33" name="__codelineno-45-33" href="#__codelineno-45-33"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-45-34" name="__codelineno-45-34" href="#__codelineno-45-34"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-45-35" name="__codelineno-45-35" href="#__codelineno-45-35"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="n">TreeNode</span><span class="w"> </span><span class="o">*</span><span class="n">choice</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-45-36" name="__codelineno-45-36" href="#__codelineno-45-36"></a><span class="w"> </span><span class="c1">// 剪枝：检查选择是否合法</span>
|
||||
<a id="__codelineno-45-37" name="__codelineno-45-37" href="#__codelineno-45-37"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-45-38" name="__codelineno-45-38" href="#__codelineno-45-38"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-45-39" name="__codelineno-45-39" href="#__codelineno-45-39"></a><span class="w"> </span><span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-45-40" name="__codelineno-45-40" href="#__codelineno-45-40"></a><span class="w"> </span><span class="c1">// 进行下一轮选择</span>
|
||||
<a id="__codelineno-45-41" name="__codelineno-45-41" href="#__codelineno-45-41"></a><span class="w"> </span><span class="n">vector</span><span class="o"><</span><span class="n">TreeNode</span><span class="w"> </span><span class="o">*></span><span class="w"> </span><span class="n">nextChoices</span><span class="p">{</span><span class="n">choice</span><span class="o">-></span><span class="n">left</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="o">-></span><span class="n">right</span><span class="p">};</span>
|
||||
<a id="__codelineno-45-42" name="__codelineno-45-42" href="#__codelineno-45-42"></a><span class="w"> </span><span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">nextChoices</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-45-43" name="__codelineno-45-43" href="#__codelineno-45-43"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-45-44" name="__codelineno-45-44" href="#__codelineno-45-44"></a><span class="w"> </span><span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-45-45" name="__codelineno-45-45" href="#__codelineno-45-45"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-45-46" name="__codelineno-45-46" href="#__codelineno-45-46"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-45-47" name="__codelineno-45-47" href="#__codelineno-45-47"></a><span class="p">}</span>
|
||||
<a id="__codelineno-45-32" name="__codelineno-45-32" href="#__codelineno-45-32"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-45-33" name="__codelineno-45-33" href="#__codelineno-45-33"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-45-34" name="__codelineno-45-34" href="#__codelineno-45-34"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="n">TreeNode</span><span class="w"> </span><span class="o">*</span><span class="n">choice</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-45-35" name="__codelineno-45-35" href="#__codelineno-45-35"></a><span class="w"> </span><span class="c1">// 剪枝：检查选择是否合法</span>
|
||||
<a id="__codelineno-45-36" name="__codelineno-45-36" href="#__codelineno-45-36"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-45-37" name="__codelineno-45-37" href="#__codelineno-45-37"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-45-38" name="__codelineno-45-38" href="#__codelineno-45-38"></a><span class="w"> </span><span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-45-39" name="__codelineno-45-39" href="#__codelineno-45-39"></a><span class="w"> </span><span class="c1">// 进行下一轮选择</span>
|
||||
<a id="__codelineno-45-40" name="__codelineno-45-40" href="#__codelineno-45-40"></a><span class="w"> </span><span class="n">vector</span><span class="o"><</span><span class="n">TreeNode</span><span class="w"> </span><span class="o">*></span><span class="w"> </span><span class="n">nextChoices</span><span class="p">{</span><span class="n">choice</span><span class="o">-></span><span class="n">left</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="o">-></span><span class="n">right</span><span class="p">};</span>
|
||||
<a id="__codelineno-45-41" name="__codelineno-45-41" href="#__codelineno-45-41"></a><span class="w"> </span><span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">nextChoices</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-45-42" name="__codelineno-45-42" href="#__codelineno-45-42"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-45-43" name="__codelineno-45-43" href="#__codelineno-45-43"></a><span class="w"> </span><span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-45-44" name="__codelineno-45-44" href="#__codelineno-45-44"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-45-45" name="__codelineno-45-45" href="#__codelineno-45-45"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-45-46" name="__codelineno-45-46" href="#__codelineno-45-46"></a><span class="p">}</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
<div class="tabbed-block">
|
||||
@ -4413,17 +4370,16 @@
|
||||
<a id="__codelineno-46-26" name="__codelineno-46-26" href="#__codelineno-46-26"></a> <span class="k">if</span> <span class="n">is_solution</span><span class="p">(</span><span class="n">state</span><span class="p">):</span>
|
||||
<a id="__codelineno-46-27" name="__codelineno-46-27" href="#__codelineno-46-27"></a> <span class="c1"># 记录解</span>
|
||||
<a id="__codelineno-46-28" name="__codelineno-46-28" href="#__codelineno-46-28"></a> <span class="n">record_solution</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="n">res</span><span class="p">)</span>
|
||||
<a id="__codelineno-46-29" name="__codelineno-46-29" href="#__codelineno-46-29"></a> <span class="k">return</span>
|
||||
<a id="__codelineno-46-30" name="__codelineno-46-30" href="#__codelineno-46-30"></a> <span class="c1"># 遍历所有选择</span>
|
||||
<a id="__codelineno-46-31" name="__codelineno-46-31" href="#__codelineno-46-31"></a> <span class="k">for</span> <span class="n">choice</span> <span class="ow">in</span> <span class="n">choices</span><span class="p">:</span>
|
||||
<a id="__codelineno-46-32" name="__codelineno-46-32" href="#__codelineno-46-32"></a> <span class="c1"># 剪枝：检查选择是否合法</span>
|
||||
<a id="__codelineno-46-33" name="__codelineno-46-33" href="#__codelineno-46-33"></a> <span class="k">if</span> <span class="n">is_valid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">):</span>
|
||||
<a id="__codelineno-46-34" name="__codelineno-46-34" href="#__codelineno-46-34"></a> <span class="c1"># 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-46-35" name="__codelineno-46-35" href="#__codelineno-46-35"></a> <span class="n">make_choice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-46-36" name="__codelineno-46-36" href="#__codelineno-46-36"></a> <span class="c1"># 进行下一轮选择</span>
|
||||
<a id="__codelineno-46-37" name="__codelineno-46-37" href="#__codelineno-46-37"></a> <span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="p">[</span><span class="n">choice</span><span class="o">.</span><span class="n">left</span><span class="p">,</span> <span class="n">choice</span><span class="o">.</span><span class="n">right</span><span class="p">],</span> <span class="n">res</span><span class="p">)</span>
|
||||
<a id="__codelineno-46-38" name="__codelineno-46-38" href="#__codelineno-46-38"></a> <span class="c1"># 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-46-39" name="__codelineno-46-39" href="#__codelineno-46-39"></a> <span class="n">undo_choice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-46-29" name="__codelineno-46-29" href="#__codelineno-46-29"></a> <span class="c1"># 遍历所有选择</span>
|
||||
<a id="__codelineno-46-30" name="__codelineno-46-30" href="#__codelineno-46-30"></a> <span class="k">for</span> <span class="n">choice</span> <span class="ow">in</span> <span class="n">choices</span><span class="p">:</span>
|
||||
<a id="__codelineno-46-31" name="__codelineno-46-31" href="#__codelineno-46-31"></a> <span class="c1"># 剪枝：检查选择是否合法</span>
|
||||
<a id="__codelineno-46-32" name="__codelineno-46-32" href="#__codelineno-46-32"></a> <span class="k">if</span> <span class="n">is_valid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">):</span>
|
||||
<a id="__codelineno-46-33" name="__codelineno-46-33" href="#__codelineno-46-33"></a> <span class="c1"># 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-46-34" name="__codelineno-46-34" href="#__codelineno-46-34"></a> <span class="n">make_choice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-46-35" name="__codelineno-46-35" href="#__codelineno-46-35"></a> <span class="c1"># 进行下一轮选择</span>
|
||||
<a id="__codelineno-46-36" name="__codelineno-46-36" href="#__codelineno-46-36"></a> <span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="p">[</span><span class="n">choice</span><span class="o">.</span><span class="n">left</span><span class="p">,</span> <span class="n">choice</span><span class="o">.</span><span class="n">right</span><span class="p">],</span> <span class="n">res</span><span class="p">)</span>
|
||||
<a id="__codelineno-46-37" name="__codelineno-46-37" href="#__codelineno-46-37"></a> <span class="c1"># 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-46-38" name="__codelineno-46-38" href="#__codelineno-46-38"></a> <span class="n">undo_choice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">)</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
<div class="tabbed-block">
|
||||
@ -4509,21 +4465,20 @@
|
||||
<a id="__codelineno-48-29" name="__codelineno-48-29" href="#__codelineno-48-29"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="nx">isSolution</span><span class="p">(</span><span class="nx">state</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-48-30" name="__codelineno-48-30" href="#__codelineno-48-30"></a><span class="w"> </span><span class="c1">// 记录解</span>
|
||||
<a id="__codelineno-48-31" name="__codelineno-48-31" href="#__codelineno-48-31"></a><span class="w"> </span><span class="nx">recordSolution</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-48-32" name="__codelineno-48-32" href="#__codelineno-48-32"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-48-33" name="__codelineno-48-33" href="#__codelineno-48-33"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-48-34" name="__codelineno-48-34" href="#__codelineno-48-34"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-48-35" name="__codelineno-48-35" href="#__codelineno-48-35"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kd">const</span><span class="w"> </span><span class="nx">choice</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="nx">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-48-36" name="__codelineno-48-36" href="#__codelineno-48-36"></a><span class="w"> </span><span class="c1">// 剪枝：检查选择是否合法</span>
|
||||
<a id="__codelineno-48-37" name="__codelineno-48-37" href="#__codelineno-48-37"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="nx">isValid</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-48-38" name="__codelineno-48-38" href="#__codelineno-48-38"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-48-39" name="__codelineno-48-39" href="#__codelineno-48-39"></a><span class="w"> </span><span class="nx">makeChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-48-40" name="__codelineno-48-40" href="#__codelineno-48-40"></a><span class="w"> </span><span class="c1">// 进行下一轮选择</span>
|
||||
<a id="__codelineno-48-41" name="__codelineno-48-41" href="#__codelineno-48-41"></a><span class="w"> </span><span class="nx">backtrack</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="p">[</span><span class="nx">choice</span><span class="p">.</span><span class="nx">left</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">.</span><span class="nx">right</span><span class="p">],</span><span class="w"> </span><span class="nx">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-48-42" name="__codelineno-48-42" href="#__codelineno-48-42"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-48-43" name="__codelineno-48-43" href="#__codelineno-48-43"></a><span class="w"> </span><span class="nx">undoChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">);</span>
|
||||
<a id="__codelineno-48-44" name="__codelineno-48-44" href="#__codelineno-48-44"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-48-45" name="__codelineno-48-45" href="#__codelineno-48-45"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-48-46" name="__codelineno-48-46" href="#__codelineno-48-46"></a><span class="p">}</span>
|
||||
<a id="__codelineno-48-32" name="__codelineno-48-32" href="#__codelineno-48-32"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-48-33" name="__codelineno-48-33" href="#__codelineno-48-33"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-48-34" name="__codelineno-48-34" href="#__codelineno-48-34"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kd">const</span><span class="w"> </span><span class="nx">choice</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="nx">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-48-35" name="__codelineno-48-35" href="#__codelineno-48-35"></a><span class="w"> </span><span class="c1">// 剪枝：检查选择是否合法</span>
|
||||
<a id="__codelineno-48-36" name="__codelineno-48-36" href="#__codelineno-48-36"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="nx">isValid</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-48-37" name="__codelineno-48-37" href="#__codelineno-48-37"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-48-38" name="__codelineno-48-38" href="#__codelineno-48-38"></a><span class="w"> </span><span class="nx">makeChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-48-39" name="__codelineno-48-39" href="#__codelineno-48-39"></a><span class="w"> </span><span class="c1">// 进行下一轮选择</span>
|
||||
<a id="__codelineno-48-40" name="__codelineno-48-40" href="#__codelineno-48-40"></a><span class="w"> </span><span class="nx">backtrack</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="p">[</span><span class="nx">choice</span><span class="p">.</span><span class="nx">left</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">.</span><span class="nx">right</span><span class="p">],</span><span class="w"> </span><span class="nx">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-48-41" name="__codelineno-48-41" href="#__codelineno-48-41"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-48-42" name="__codelineno-48-42" href="#__codelineno-48-42"></a><span class="w"> </span><span class="nx">undoChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">);</span>
|
||||
<a id="__codelineno-48-43" name="__codelineno-48-43" href="#__codelineno-48-43"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-48-44" name="__codelineno-48-44" href="#__codelineno-48-44"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-48-45" name="__codelineno-48-45" href="#__codelineno-48-45"></a><span class="p">}</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
<div class="tabbed-block">
|
||||
@ -4562,21 +4517,20 @@
|
||||
<a id="__codelineno-49-33" name="__codelineno-49-33" href="#__codelineno-49-33"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="nx">isSolution</span><span class="p">(</span><span class="nx">state</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-49-34" name="__codelineno-49-34" href="#__codelineno-49-34"></a><span class="w"> </span><span class="c1">// 记录解</span>
|
||||
<a id="__codelineno-49-35" name="__codelineno-49-35" href="#__codelineno-49-35"></a><span class="w"> </span><span class="nx">recordSolution</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-49-36" name="__codelineno-49-36" href="#__codelineno-49-36"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-49-37" name="__codelineno-49-37" href="#__codelineno-49-37"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-49-38" name="__codelineno-49-38" href="#__codelineno-49-38"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-49-39" name="__codelineno-49-39" href="#__codelineno-49-39"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kd">const</span><span class="w"> </span><span class="nx">choice</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="nx">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-49-40" name="__codelineno-49-40" href="#__codelineno-49-40"></a><span class="w"> </span><span class="c1">// 剪枝：检查选择是否合法</span>
|
||||
<a id="__codelineno-49-41" name="__codelineno-49-41" href="#__codelineno-49-41"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="nx">isValid</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-49-42" name="__codelineno-49-42" href="#__codelineno-49-42"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-49-43" name="__codelineno-49-43" href="#__codelineno-49-43"></a><span class="w"> </span><span class="nx">makeChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-49-44" name="__codelineno-49-44" href="#__codelineno-49-44"></a><span class="w"> </span><span class="c1">// 进行下一轮选择</span>
|
||||
<a id="__codelineno-49-45" name="__codelineno-49-45" href="#__codelineno-49-45"></a><span class="w"> </span><span class="nx">backtrack</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="p">[</span><span class="nx">choice</span><span class="p">.</span><span class="nx">left</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">.</span><span class="nx">right</span><span class="p">],</span><span class="w"> </span><span class="nx">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-49-46" name="__codelineno-49-46" href="#__codelineno-49-46"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-49-47" name="__codelineno-49-47" href="#__codelineno-49-47"></a><span class="w"> </span><span class="nx">undoChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">);</span>
|
||||
<a id="__codelineno-49-48" name="__codelineno-49-48" href="#__codelineno-49-48"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-49-49" name="__codelineno-49-49" href="#__codelineno-49-49"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-49-50" name="__codelineno-49-50" href="#__codelineno-49-50"></a><span class="p">}</span>
|
||||
<a id="__codelineno-49-36" name="__codelineno-49-36" href="#__codelineno-49-36"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-49-37" name="__codelineno-49-37" href="#__codelineno-49-37"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-49-38" name="__codelineno-49-38" href="#__codelineno-49-38"></a><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="kd">const</span><span class="w"> </span><span class="nx">choice</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="nx">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-49-39" name="__codelineno-49-39" href="#__codelineno-49-39"></a><span class="w"> </span><span class="c1">// 剪枝：检查选择是否合法</span>
|
||||
<a id="__codelineno-49-40" name="__codelineno-49-40" href="#__codelineno-49-40"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="nx">isValid</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-49-41" name="__codelineno-49-41" href="#__codelineno-49-41"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-49-42" name="__codelineno-49-42" href="#__codelineno-49-42"></a><span class="w"> </span><span class="nx">makeChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-49-43" name="__codelineno-49-43" href="#__codelineno-49-43"></a><span class="w"> </span><span class="c1">// 进行下一轮选择</span>
|
||||
<a id="__codelineno-49-44" name="__codelineno-49-44" href="#__codelineno-49-44"></a><span class="w"> </span><span class="nx">backtrack</span><span class="p">(</span><span class="nx">state</span><span class="p">,</span><span class="w"> </span><span class="p">[</span><span class="nx">choice</span><span class="p">.</span><span class="nx">left</span><span class="p">,</span><span class="w"> </span><span class="nx">choice</span><span class="p">.</span><span class="nx">right</span><span class="p">],</span><span class="w"> </span><span class="nx">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-49-45" name="__codelineno-49-45" href="#__codelineno-49-45"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-49-46" name="__codelineno-49-46" href="#__codelineno-49-46"></a><span class="w"> </span><span class="nx">undoChoice</span><span class="p">(</span><span class="nx">state</span><span class="p">);</span>
|
||||
<a id="__codelineno-49-47" name="__codelineno-49-47" href="#__codelineno-49-47"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-49-48" name="__codelineno-49-48" href="#__codelineno-49-48"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-49-49" name="__codelineno-49-49" href="#__codelineno-49-49"></a><span class="p">}</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
<div class="tabbed-block">
|
||||
@ -4625,21 +4579,20 @@
|
||||
<a id="__codelineno-51-29" name="__codelineno-51-29" href="#__codelineno-51-29"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isSolution</span><span class="p">(</span><span class="n">state</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-51-30" name="__codelineno-51-30" href="#__codelineno-51-30"></a><span class="w"> </span><span class="c1">// 记录解</span>
|
||||
<a id="__codelineno-51-31" name="__codelineno-51-31" href="#__codelineno-51-31"></a><span class="w"> </span><span class="n">recordSolution</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-51-32" name="__codelineno-51-32" href="#__codelineno-51-32"></a><span class="w"> </span><span class="k">return</span><span class="p">;</span>
|
||||
<a id="__codelineno-51-33" name="__codelineno-51-33" href="#__codelineno-51-33"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-51-34" name="__codelineno-51-34" href="#__codelineno-51-34"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-51-35" name="__codelineno-51-35" href="#__codelineno-51-35"></a><span class="w"> </span><span class="k">foreach</span><span class="w"> </span><span class="p">(</span><span class="n">TreeNode</span><span class="w"> </span><span class="n">choice</span><span class="w"> </span><span class="k">in</span><span class="w"> </span><span class="n">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-51-36" name="__codelineno-51-36" href="#__codelineno-51-36"></a><span class="w"> </span><span class="c1">// 剪枝：检查选择是否合法</span>
|
||||
<a id="__codelineno-51-37" name="__codelineno-51-37" href="#__codelineno-51-37"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-51-38" name="__codelineno-51-38" href="#__codelineno-51-38"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-51-39" name="__codelineno-51-39" href="#__codelineno-51-39"></a><span class="w"> </span><span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-51-40" name="__codelineno-51-40" href="#__codelineno-51-40"></a><span class="w"> </span><span class="c1">// 进行下一轮选择</span>
|
||||
<a id="__codelineno-51-41" name="__codelineno-51-41" href="#__codelineno-51-41"></a><span class="w"> </span><span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">List</span><span class="o"><</span><span class="n">TreeNode</span><span class="o">></span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="n">choice</span><span class="p">.</span><span class="n">left</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">.</span><span class="n">right</span><span class="w"> </span><span class="p">},</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-51-42" name="__codelineno-51-42" href="#__codelineno-51-42"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-51-43" name="__codelineno-51-43" href="#__codelineno-51-43"></a><span class="w"> </span><span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-51-44" name="__codelineno-51-44" href="#__codelineno-51-44"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-51-45" name="__codelineno-51-45" href="#__codelineno-51-45"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-51-46" name="__codelineno-51-46" href="#__codelineno-51-46"></a><span class="p">}</span>
|
||||
<a id="__codelineno-51-32" name="__codelineno-51-32" href="#__codelineno-51-32"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-51-33" name="__codelineno-51-33" href="#__codelineno-51-33"></a><span class="w"> </span><span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-51-34" name="__codelineno-51-34" href="#__codelineno-51-34"></a><span class="w"> </span><span class="k">foreach</span><span class="w"> </span><span class="p">(</span><span class="n">TreeNode</span><span class="w"> </span><span class="n">choice</span><span class="w"> </span><span class="k">in</span><span class="w"> </span><span class="n">choices</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-51-35" name="__codelineno-51-35" href="#__codelineno-51-35"></a><span class="w"> </span><span class="c1">// 剪枝：检查选择是否合法</span>
|
||||
<a id="__codelineno-51-36" name="__codelineno-51-36" href="#__codelineno-51-36"></a><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">))</span><span class="w"> </span><span class="p">{</span>
|
||||
<a id="__codelineno-51-37" name="__codelineno-51-37" href="#__codelineno-51-37"></a><span class="w"> </span><span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-51-38" name="__codelineno-51-38" href="#__codelineno-51-38"></a><span class="w"> </span><span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-51-39" name="__codelineno-51-39" href="#__codelineno-51-39"></a><span class="w"> </span><span class="c1">// 进行下一轮选择</span>
|
||||
<a id="__codelineno-51-40" name="__codelineno-51-40" href="#__codelineno-51-40"></a><span class="w"> </span><span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="k">new</span><span class="w"> </span><span class="n">List</span><span class="o"><</span><span class="n">TreeNode</span><span class="o">></span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="n">choice</span><span class="p">.</span><span class="n">left</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">.</span><span class="n">right</span><span class="w"> </span><span class="p">},</span><span class="w"> </span><span class="n">res</span><span class="p">);</span>
|
||||
<a id="__codelineno-51-41" name="__codelineno-51-41" href="#__codelineno-51-41"></a><span class="w"> </span><span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-51-42" name="__codelineno-51-42" href="#__codelineno-51-42"></a><span class="w"> </span><span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">,</span><span class="w"> </span><span class="n">choice</span><span class="p">);</span>
|
||||
<a id="__codelineno-51-43" name="__codelineno-51-43" href="#__codelineno-51-43"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-51-44" name="__codelineno-51-44" href="#__codelineno-51-44"></a><span class="w"> </span><span class="p">}</span>
|
||||
<a id="__codelineno-51-45" name="__codelineno-51-45" href="#__codelineno-51-45"></a><span class="p">}</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
<div class="tabbed-block">
|
||||
@ -4673,21 +4626,20 @@
|
||||
<a id="__codelineno-52-28" name="__codelineno-52-28" href="#__codelineno-52-28"></a> <span class="c1">// 检查是否为解</span>
|
||||
<a id="__codelineno-52-29" name="__codelineno-52-29" href="#__codelineno-52-29"></a> <span class="k">if</span> <span class="n">isSolution</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="n">state</span><span class="p">)</span> <span class="p">{</span>
|
||||
<a id="__codelineno-52-30" name="__codelineno-52-30" href="#__codelineno-52-30"></a> <span class="n">recordSolution</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="n">state</span><span class="p">,</span> <span class="n">res</span><span class="p">:</span> <span class="p">&</span><span class="n">res</span><span class="p">)</span>
|
||||
<a id="__codelineno-52-31" name="__codelineno-52-31" href="#__codelineno-52-31"></a> <span class="k">return</span>
|
||||
<a id="__codelineno-52-32" name="__codelineno-52-32" href="#__codelineno-52-32"></a> <span class="p">}</span>
|
||||
<a id="__codelineno-52-33" name="__codelineno-52-33" href="#__codelineno-52-33"></a> <span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-52-34" name="__codelineno-52-34" href="#__codelineno-52-34"></a> <span class="k">for</span> <span class="n">choice</span> <span class="k">in</span> <span class="n">choices</span> <span class="p">{</span>
|
||||
<a id="__codelineno-52-35" name="__codelineno-52-35" href="#__codelineno-52-35"></a> <span class="c1">// 剪枝：检查选择是否合法</span>
|
||||
<a id="__codelineno-52-36" name="__codelineno-52-36" href="#__codelineno-52-36"></a> <span class="k">if</span> <span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">:</span> <span class="n">choice</span><span class="p">)</span> <span class="p">{</span>
|
||||
<a id="__codelineno-52-37" name="__codelineno-52-37" href="#__codelineno-52-37"></a> <span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-52-38" name="__codelineno-52-38" href="#__codelineno-52-38"></a> <span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="p">&</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">:</span> <span class="n">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-52-39" name="__codelineno-52-39" href="#__codelineno-52-39"></a> <span class="c1">// 进行下一轮选择</span>
|
||||
<a id="__codelineno-52-40" name="__codelineno-52-40" href="#__codelineno-52-40"></a> <span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="p">&</span><span class="n">state</span><span class="p">,</span> <span class="n">choices</span><span class="p">:</span> <span class="p">[</span><span class="n">choice</span><span class="p">.</span><span class="kr">left</span><span class="p">,</span> <span class="n">choice</span><span class="p">.</span><span class="kr">right</span><span class="p">].</span><span class="n">compactMap</span> <span class="p">{</span> <span class="nv">$0</span> <span class="p">},</span> <span class="n">res</span><span class="p">:</span> <span class="p">&</span><span class="n">res</span><span class="p">)</span>
|
||||
<a id="__codelineno-52-41" name="__codelineno-52-41" href="#__codelineno-52-41"></a> <span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-52-42" name="__codelineno-52-42" href="#__codelineno-52-42"></a> <span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="p">&</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">:</span> <span class="n">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-52-43" name="__codelineno-52-43" href="#__codelineno-52-43"></a> <span class="p">}</span>
|
||||
<a id="__codelineno-52-44" name="__codelineno-52-44" href="#__codelineno-52-44"></a> <span class="p">}</span>
|
||||
<a id="__codelineno-52-45" name="__codelineno-52-45" href="#__codelineno-52-45"></a><span class="p">}</span>
|
||||
<a id="__codelineno-52-31" name="__codelineno-52-31" href="#__codelineno-52-31"></a> <span class="p">}</span>
|
||||
<a id="__codelineno-52-32" name="__codelineno-52-32" href="#__codelineno-52-32"></a> <span class="c1">// 遍历所有选择</span>
|
||||
<a id="__codelineno-52-33" name="__codelineno-52-33" href="#__codelineno-52-33"></a> <span class="k">for</span> <span class="n">choice</span> <span class="k">in</span> <span class="n">choices</span> <span class="p">{</span>
|
||||
<a id="__codelineno-52-34" name="__codelineno-52-34" href="#__codelineno-52-34"></a> <span class="c1">// 剪枝：检查选择是否合法</span>
|
||||
<a id="__codelineno-52-35" name="__codelineno-52-35" href="#__codelineno-52-35"></a> <span class="k">if</span> <span class="n">isValid</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">:</span> <span class="n">choice</span><span class="p">)</span> <span class="p">{</span>
|
||||
<a id="__codelineno-52-36" name="__codelineno-52-36" href="#__codelineno-52-36"></a> <span class="c1">// 尝试：做出选择，更新状态</span>
|
||||
<a id="__codelineno-52-37" name="__codelineno-52-37" href="#__codelineno-52-37"></a> <span class="n">makeChoice</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="p">&</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">:</span> <span class="n">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-52-38" name="__codelineno-52-38" href="#__codelineno-52-38"></a> <span class="c1">// 进行下一轮选择</span>
|
||||
<a id="__codelineno-52-39" name="__codelineno-52-39" href="#__codelineno-52-39"></a> <span class="n">backtrack</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="p">&</span><span class="n">state</span><span class="p">,</span> <span class="n">choices</span><span class="p">:</span> <span class="p">[</span><span class="n">choice</span><span class="p">.</span><span class="kr">left</span><span class="p">,</span> <span class="n">choice</span><span class="p">.</span><span class="kr">right</span><span class="p">].</span><span class="n">compactMap</span> <span class="p">{</span> <span class="nv">$0</span> <span class="p">},</span> <span class="n">res</span><span class="p">:</span> <span class="p">&</span><span class="n">res</span><span class="p">)</span>
|
||||
<a id="__codelineno-52-40" name="__codelineno-52-40" href="#__codelineno-52-40"></a> <span class="c1">// 回退：撤销选择，恢复到之前的状态</span>
|
||||
<a id="__codelineno-52-41" name="__codelineno-52-41" href="#__codelineno-52-41"></a> <span class="n">undoChoice</span><span class="p">(</span><span class="n">state</span><span class="p">:</span> <span class="p">&</span><span class="n">state</span><span class="p">,</span> <span class="n">choice</span><span class="p">:</span> <span class="n">choice</span><span class="p">)</span>
|
||||
<a id="__codelineno-52-42" name="__codelineno-52-42" href="#__codelineno-52-42"></a> <span class="p">}</span>
|
||||
<a id="__codelineno-52-43" name="__codelineno-52-43" href="#__codelineno-52-43"></a> <span class="p">}</span>
|
||||
<a id="__codelineno-52-44" name="__codelineno-52-44" href="#__codelineno-52-44"></a><span class="p">}</span>
|
||||
</code></pre></div>
|
||||
</div>
|
||||
<div class="tabbed-block">
|
||||
@ -4720,7 +4672,58 @@
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<p>相比基于前序遍历的代码实现，基于回溯算法框架的代码实现虽然显得啰嗦，但通用性更好。实际上，<strong>许多回溯问题都可以在该框架下解决</strong>。我们只需根据具体问题来定义 <code>state</code> 和 <code>choices</code> ，并实现框架中的各个方法。</p>
|
||||
<p>根据题意，当找到值为 7 的节点后应该继续搜索，<strong>因此我们需要将记录解之后的 <code>return</code> 语句删除</strong>。下图对比了保留或删除 <code>return</code> 语句的搜索过程。</p>
|
||||
<p><img alt="保留与删除 return 的搜索过程对比" src="../backtracking_algorithm.assets/backtrack_remove_return_or_not.png" /></p>
|
||||
<p align="center"> Fig. 保留与删除 return 的搜索过程对比 </p>
|
||||
|
||||
<p>相比基于前序遍历的代码实现，基于回溯算法框架的代码实现虽然显得啰嗦，但通用性更好。实际上，<strong>许多回溯问题都可以在该框架下解决</strong>。我们只需根据具体问题来定义 <code>state</code> 和 <code>choices</code> ，并实现框架中的各个方法即可。</p>
|
||||
<h2 id="1314">13.1.4. 常用术语<a class="headerlink" href="#1314" title="Permanent link">¶</a></h2>
|
||||
<p>为了更清晰地分析算法问题，我们总结一下回溯算法中常用术语的含义，并对照例题三给出对应示例。</p>
|
||||
<table>
|
||||
<thead>
|
||||
<tr>
|
||||
<th>名词</th>
|
||||
<th>定义</th>
|
||||
<th>例题三</th>
|
||||
</tr>
|
||||
</thead>
|
||||
<tbody>
|
||||
<tr>
|
||||
<td>解 Solution</td>
|
||||
<td>解是满足问题特定条件的答案，可能有一个或多个</td>
|
||||
<td>根节点到节点 <span class="arithmatex">\(7\)</span> 的满足约束条件的所有路径</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>约束条件 Constraint</td>
|
||||
<td>约束条件是问题中限制解的可行性的条件，通常用于剪枝</td>
|
||||
<td>路径中不包含节点 <span class="arithmatex">\(3\)</span> ，只包含一个节点 <span class="arithmatex">\(7\)</span></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>状态 State</td>
|
||||
<td>状态表示问题在某一时刻的情况，包括已经做出的选择</td>
|
||||
<td>当前已访问的节点路径，即 <code>path</code> 节点列表</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>尝试 Attempt</td>
|
||||
<td>尝试是根据可用选择来探索解空间的过程，包括做出选择，更新状态，检查是否为解</td>
|
||||
<td>递归访问左（右）子节点，将节点添加进 <code>path</code> ，判断节点的值是否为 <span class="arithmatex">\(7\)</span></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>回退 Backtracking</td>
|
||||
<td>回退指遇到不满足约束条件的状态时，撤销前面做出的选择，回到上一个状态</td>
|
||||
<td>当越过叶结点、结束结点访问、遇到值为 <span class="arithmatex">\(3\)</span> 的节点时终止搜索，函数返回</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>剪枝 Pruning</td>
|
||||
<td>剪枝是根据问题特性和约束条件避免无意义的搜索路径的方法，可提高搜索效率</td>
|
||||
<td>当遇到值为 <span class="arithmatex">\(3\)</span> 的节点时，则终止继续搜索</td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
<div class="admonition tip">
|
||||
<p class="admonition-title">Tip</p>
|
||||
<p>问题、解、状态等概念是通用的，在分治、回溯、动态规划、贪心等算法中都有涉及。</p>
|
||||
</div>
|
||||
<h2 id="1315">13.1.5. 优势与局限性<a class="headerlink" href="#1315" title="Permanent link">¶</a></h2>
|
||||
<p>回溯算法本质上是一种深度优先搜索算法，它尝试所有可能的解决方案直到找到满足条件的解。这种方法的优势在于它能够找到所有可能的解决方案，而且在合理的剪枝操作下，具有很高的效率。</p>
|
||||
<p>然而，在处理大规模或者复杂问题时，<strong>回溯算法的运行效率可能难以接受</strong>。</p>
|
||||
|
||||
Reference in New Issue
Block a user