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Merge pull request #1238 from GitHubQAQ/master
#0383.赎金信.md 更新:C++代码添加预判断长度的代码
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@ -227,7 +227,7 @@ private:
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public:
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vector<string> restoreIpAddresses(string s) {
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result.clear();
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if (s.size() > 12) return result; // 算是剪枝了
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if (s.size() < 4 || s.size() > 12) return result; // 算是剪枝了
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backtracking(s, 0, 0);
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return result;
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}
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@ -103,7 +103,7 @@ TreeNode* traversal (vector<int>& inorder, vector<int>& postorder) {
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中序数组相对比较好切,找到切割点(后序数组的最后一个元素)在中序数组的位置,然后切割,如下代码中我坚持左闭右开的原则:
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```C++
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```CPP
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// 找到中序遍历的切割点
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int delimiterIndex;
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for (delimiterIndex = 0; delimiterIndex < inorder.size(); delimiterIndex++) {
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@ -130,7 +130,7 @@ vector<int> rightInorder(inorder.begin() + delimiterIndex + 1, inorder.end() );
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代码如下:
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```
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```CPP
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// postorder 舍弃末尾元素,因为这个元素就是中间节点,已经用过了
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postorder.resize(postorder.size() - 1);
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@ -144,7 +144,7 @@ vector<int> rightPostorder(postorder.begin() + leftInorder.size(), postorder.end
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接下来可以递归了,代码如下:
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```
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```CPP
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root->left = traversal(leftInorder, leftPostorder);
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root->right = traversal(rightInorder, rightPostorder);
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```
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@ -84,6 +84,10 @@ class Solution {
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public:
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bool canConstruct(string ransomNote, string magazine) {
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int record[26] = {0};
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//add
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if (ransomNote.size() > magazine.size()) {
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return false;
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}
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for (int i = 0; i < magazine.length(); i++) {
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// 通过recode数据记录 magazine里各个字符出现次数
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record[magazine[i]-'a'] ++;
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