From a3ba386ad6037ffafb80e2dac466b0b37146e304 Mon Sep 17 00:00:00 2001 From: nanhuaibeian <49868746+nanhuaibeian@users.noreply.github.com> Date: Wed, 12 May 2021 21:59:18 +0800 Subject: [PATCH 01/13] =?UTF-8?q?Update=200017.=E7=94=B5=E8=AF=9D=E5=8F=B7?= =?UTF-8?q?=E7=A0=81=E7=9A=84=E5=AD=97=E6=AF=8D=E7=BB=84=E5=90=88.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0017.电话号码的字母组合.md | 38 ++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/problems/0017.电话号码的字母组合.md b/problems/0017.电话号码的字母组合.md index 6f51a181..76d5655d 100644 --- a/problems/0017.电话号码的字母组合.md +++ b/problems/0017.电话号码的字母组合.md @@ -240,7 +240,45 @@ public: Java： +```Java +class Solution { + //设置全局列表存储最后的结果 + List list = new ArrayList<>(); + + public List letterCombinations(String digits) { + if (digits == null || digits.length() == 0) { + return list; + } + //初始对应所有的数字，为了直接对应2-9，新增了两个无效的字符串"" + String[] numString = {"", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"}; + //迭代处理 + backTracking(digits, numString, 0); + return list; + + } + + //每次迭代获取一个字符串，所以会设计大量的字符串拼接，所以这里选择更为高效的 StringBuild + StringBuilder temp = new StringBuilder(); + + //比如digits如果为"23",num 为0，则str表示2对应的 abc + public void backTracking(String digits, String[] numString, int num) { + //遍历全部一次记录一次得到的字符串 + if (num == digits.length()) { + list.add(temp.toString()); + return; + } + //str 表示当前num对应的字符串 + String str = numString[digits.charAt(num) - '0']; + for (int i = 0; i < str.length(); i++) { + temp.append(str.charAt(i)); + backTracking(digits, numString, num + 1); + //剔除末尾的继续尝试 + temp.deleteCharAt(temp.length() - 1); + } + } +} +``` Python： From 5a799c674ee78df7c25247c29ef3667592d7980b Mon Sep 17 00:00:00 2001 From: nanhuaibeian <49868746+nanhuaibeian@users.noreply.github.com> Date: Wed, 12 May 2021 22:20:54 +0800 Subject: [PATCH 02/13] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200017.=E7=94=B5?= =?UTF-8?q?=E8=AF=9D=E5=8F=B7=E7=A0=81=E7=9A=84=E5=AD=97=E6=AF=8D=E7=BB=84?= =?UTF-8?q?=E5=90=88.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0017.电话号码的字母组合.md | 1 - 1 file changed, 1 deletion(-) diff --git a/problems/0017.电话号码的字母组合.md b/problems/0017.电话号码的字母组合.md index 76d5655d..5e856df4 100644 --- a/problems/0017.电话号码的字母组合.md +++ b/problems/0017.电话号码的字母组合.md @@ -242,7 +242,6 @@ public: Java： ```Java class Solution { - //设置全局列表存储最后的结果 List list = new ArrayList<>(); From c2fd043de06e9151863e1f9ceffcddae0f180d11 Mon Sep 17 00:00:00 2001 From: nanhuaibeian <49868746+nanhuaibeian@users.noreply.github.com> Date: Wed, 12 May 2021 22:23:51 +0800 Subject: [PATCH 03/13] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200017.=E7=94=B5?= =?UTF-8?q?=E8=AF=9D=E5=8F=B7=E7=A0=81=E7=9A=84=E5=AD=97=E6=AF=8D=E7=BB=84?= =?UTF-8?q?=E5=90=88.md=20Java=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0017.电话号码的字母组合.md | 2 ++ 1 file changed, 2 insertions(+) diff --git a/problems/0017.电话号码的字母组合.md b/problems/0017.电话号码的字母组合.md index 5e856df4..f06ed80a 100644 --- a/problems/0017.电话号码的字母组合.md +++ b/problems/0017.电话号码的字母组合.md @@ -242,6 +242,7 @@ public: Java： ```Java class Solution { + //设置全局列表存储最后的结果 List list = new ArrayList<>(); @@ -271,6 +272,7 @@ class Solution { String str = numString[digits.charAt(num) - '0']; for (int i = 0; i < str.length(); i++) { temp.append(str.charAt(i)); + //回溯 backTracking(digits, numString, num + 1); //剔除末尾的继续尝试 temp.deleteCharAt(temp.length() - 1); From 2e2f7735d6b99bb73f0b96f11c205fe70fa774a2 Mon Sep 17 00:00:00 2001 From: nanhuaibeian <49868746+nanhuaibeian@users.noreply.github.com> Date: Thu, 13 May 2021 09:37:33 +0800 Subject: [PATCH 04/13] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=E5=89=91=E6=8C=87Offer?= =?UTF-8?q?05.=E6=9B=BF=E6=8D=A2=E7=A9=BA=E6=A0=BC.md=20Java=E7=89=88?= =?UTF-8?q?=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/剑指Offer05.替换空格.md | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/problems/剑指Offer05.替换空格.md b/problems/剑指Offer05.替换空格.md index 7881adf3..5f89241b 100644 --- a/problems/剑指Offer05.替换空格.md +++ b/problems/剑指Offer05.替换空格.md @@ -129,7 +129,26 @@ for (int i = 0; i < a.size(); i++) { Java： - +```Java +//使用一个新的对象，复制 str，复制的过程对其判断，是空格则替换，否则直接复制，类似于数组复制 +public static String replaceSpace(StringBuffer str) { + if (str == null) { + return null; + } + //选用 StringBuilder 单线程使用，比较快，选不选都行 + StringBuilder sb = new StringBuilder(); + //使用 sb 逐个复制 str ，碰到空格则替换，否则直接复制 + for (int i = 0; i < str.length(); i++) { + //str.charAt(i) 为 char 类型，为了比较需要将其转为和 " " 相同的字符串类型 + if (" ".equals(String.valueOf(str.charAt(i)))){ + sb.append("%20"); + } else { + sb.append(str.charAt(i)); + } + } + return sb.toString(); + } +``` Python： From 4a582a32fbc984e0bde728ba7e787430af437f9d Mon Sep 17 00:00:00 2001 From: nanhuaibeian <49868746+nanhuaibeian@users.noreply.github.com> Date: Thu, 13 May 2021 09:40:40 +0800 Subject: [PATCH 05/13] =?UTF-8?q?=E6=B7=BB=E5=8A=A01047.=E5=88=A0=E9=99=A4?= =?UTF-8?q?=E5=AD=97=E7=AC=A6=E4=B8=B2=E4=B8=AD=E7=9A=84=E6=89=80=E6=9C=89?= =?UTF-8?q?=E7=9B=B8=E9=82=BB=E9=87=8D=E5=A4=8D=E9=A1=B9=20Java=20?= =?UTF-8?q?=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...除字符串中的所有相邻重复项.md | 23 ++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/problems/1047.删除字符串中的所有相邻重复项.md b/problems/1047.删除字符串中的所有相邻重复项.md index 7a06f02d..d5a8c4ed 100644 --- a/problems/1047.删除字符串中的所有相邻重复项.md +++ b/problems/1047.删除字符串中的所有相邻重复项.md @@ -122,7 +122,28 @@ public: Java： - +```Java +class Solution { + public String removeDuplicates(String S) { + Deque deque = new LinkedList<>(); + char ch; + for (int i = 0; i < S.length(); i++) { + ch = S.charAt(i); + if (deque.isEmpty() || deque.peek() != ch) { + deque.push(ch); + } else { + deque.pop(); + } + } + String str = ""; + //剩余的元素即为不重复的元素 + while (!deque.isEmpty()) { + str = deque.pop() + str; + } + return str; + } +} +``` Python： From ebbeb35b1164003fb9367d90c7647e2e567f5ff8 Mon Sep 17 00:00:00 2001 From: nanhuaibeian <49868746+nanhuaibeian@users.noreply.github.com> Date: Thu, 13 May 2021 09:43:25 +0800 Subject: [PATCH 06/13] =?UTF-8?q?=E6=B7=BB=E5=8A=A00239.=E6=BB=91=E5=8A=A8?= =?UTF-8?q?=E7=AA=97=E5=8F=A3=E6=9C=80=E5=A4=A7=E5=80=BC=20Java=E7=89=88?= =?UTF-8?q?=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0239.滑动窗口最大值.md | 53 ++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) diff --git a/problems/0239.滑动窗口最大值.md b/problems/0239.滑动窗口最大值.md index 709fa09e..781bfa6f 100644 --- a/problems/0239.滑动窗口最大值.md +++ b/problems/0239.滑动窗口最大值.md @@ -207,7 +207,60 @@ public: Java： +```Java +//自定义数组 +class MyQueue { + Deque deque = new LinkedList<>(); + //弹出元素时，比较当前要弹出的数值是否等于队列出口的数值，如果相等则弹出 + //同时判断队列当前是否为空 + void poll(int val) { + if (!deque.isEmpty() && val == deque.peek()) { + deque.poll(); + } + } + //添加元素时，如果要添加的元素大于入口处的元素，就将入口元素弹出 + //保证队列元素单调递减 + //比如此时队列元素3,1，2将要入队，比1大，所以1弹出，此时队列：3,2 + void add(int val) { + while (!deque.isEmpty() && val > deque.getLast()) { + deque.removeLast(); + } + deque.add(val); + } + //队列队顶元素始终为最大值 + int peek() { + return deque.peek(); + } +} +class Solution { + public int[] maxSlidingWindow(int[] nums, int k) { + if (nums.length == 1) { + return nums; + } + int len = nums.length - k + 1; + //存放结果元素的数组 + int[] res = new int[len]; + int num = 0; + //自定义队列 + MyQueue myQueue = new MyQueue(); + //先将前k的元素放入队列 + for (int i = 0; i < k; i++) { + myQueue.add(nums[i]); + } + res[num++] = myQueue.peek(); + for (int i = k; i < nums.length; i++) { + //滑动窗口移除最前面的元素，移除是判断该元素是否放入队列 + myQueue.poll(nums[i - k]); + //滑动窗口加入最后面的元素 + myQueue.add(nums[i]); + //记录对应的最大值 + res[num++] = myQueue.peek(); + } + return res; + } +} +``` Python： From d646ad263d9bf421559479b3d73458b586dca691 Mon Sep 17 00:00:00 2001 From: nanhuaibeian <49868746+nanhuaibeian@users.noreply.github.com> Date: Thu, 13 May 2021 09:45:18 +0800 Subject: [PATCH 07/13] =?UTF-8?q?=E6=B7=BB=E5=8A=A00376.=E6=91=86=E5=8A=A8?= =?UTF-8?q?=E5=BA=8F=E5=88=97=20Java=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0376.摆动序列.md | 26 +++++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-) diff --git a/problems/0376.摆动序列.md b/problems/0376.摆动序列.md index 6ae76526..fa90142d 100644 --- a/problems/0376.摆动序列.md +++ b/problems/0376.摆动序列.md @@ -111,7 +111,31 @@ public: Java： - +```Java +class Solution { + public int wiggleMaxLength(int[] nums) { + if (nums == null || nums.length <= 1) { + return nums.length; + } + //当前差值 + int curDiff = 0; + //上一个差值 + int preDiff = 0; + int count = 1; + for (int i = 1; i < nums.length; i++) { + //得到当前差值 + curDiff = nums[i] - nums[i - 1]; + //如果当前差值和上一个差值为一正一负 + //等于0的情况表示初始时的preDiff + if ((curDiff > 0 && preDiff <= 0) || (curDiff < 0 && preDiff >= 0)) { + count++; + preDiff = curDiff; + } + } + return count; + } +} +``` Python： From 538aaf527ed61cedf6ee09466e2bb81fe6177f99 Mon Sep 17 00:00:00 2001 From: nanhuaibeian <49868746+nanhuaibeian@users.noreply.github.com> Date: Thu, 13 May 2021 09:46:24 +0800 Subject: [PATCH 08/13] =?UTF-8?q?=E6=B7=BB=E5=8A=A00279.=E5=AE=8C=E5=85=A8?= =?UTF-8?q?=E5=B9=B3=E6=96=B9=E6=95=B0=20Java=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0279.完全平方数.md | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/problems/0279.完全平方数.md b/problems/0279.完全平方数.md index 39260926..d72e9099 100644 --- a/problems/0279.完全平方数.md +++ b/problems/0279.完全平方数.md @@ -159,7 +159,28 @@ public: Java： - +```Java +class Solution { + public int numSquares(int n) { + int max = Integer.MAX_VALUE; + int[] dp = new int[n + 1]; + //初始化 + for (int j = 0; j <= n; j++) { + dp[j] = max; + } + //当和为0时，组合的个数为0 + dp[0] = 0; + for (int i = 1; i * i <= n; i++) { + for (int j = i * i; j <= n; j++) { + if (dp[j - i * i] != max) { + dp[j] = Math.min(dp[j], dp[j - i * i] + 1); + } + } + } + return dp[n]; + } +} +``` Python： From 9bae5a96c092f8dd30f326f9cfa5ded5408f7e69 Mon Sep 17 00:00:00 2001 From: nanhuaibeian <49868746+nanhuaibeian@users.noreply.github.com> Date: Thu, 13 May 2021 09:47:49 +0800 Subject: [PATCH 09/13] =?UTF-8?q?Update=200096.=E4=B8=8D=E5=90=8C=E7=9A=84?= =?UTF-8?q?=E4=BA=8C=E5=8F=89=E6=90=9C=E7=B4=A2=E6=A0=91.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 添加0096.不同的二叉搜索树 Java版本 --- problems/0096.不同的二叉搜索树.md | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/problems/0096.不同的二叉搜索树.md b/problems/0096.不同的二叉搜索树.md index 2764277c..98c993e4 100644 --- a/problems/0096.不同的二叉搜索树.md +++ b/problems/0096.不同的二叉搜索树.md @@ -165,7 +165,26 @@ public: Java： - +```Java +class Solution { + public int numTrees(int n) { + //初始化 dp 数组 + int[] dp = new int[n + 1]; + //初始化0个节点和1个节点的情况 + dp[0] = 1; + dp[1] = 1; + //遍历 + for (int i = 2; i <= n; i++) { + for (int j = 1; j <= i; j++) { + //对于第i个节点，需要考虑1作为根节点直到i作为根节点的情况，所以需要累加 + //一共i个节点，对于根节点j时,左子树的节点个数为j-1，右子树的节点个数为i-j + dp[i] += dp[j - 1] * dp[i - j]; + } + } + return dp[n]; + } +} +``` Python： From 231baca72ae08395e02602243f335004d9b63fe1 Mon Sep 17 00:00:00 2001 From: nanhuaibeian <49868746+nanhuaibeian@users.noreply.github.com> Date: Thu, 13 May 2021 09:48:45 +0800 Subject: [PATCH 10/13] =?UTF-8?q?=E6=B7=BB=E5=8A=A00096.=E4=B8=8D=E5=90=8C?= =?UTF-8?q?=E7=9A=84=E4=BA=8C=E5=8F=89=E6=90=9C=E7=B4=A2=E6=A0=91=20Java?= =?UTF-8?q?=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0096.不同的二叉搜索树.md | 1 - 1 file changed, 1 deletion(-) diff --git a/problems/0096.不同的二叉搜索树.md b/problems/0096.不同的二叉搜索树.md index 98c993e4..7dea8fb0 100644 --- a/problems/0096.不同的二叉搜索树.md +++ b/problems/0096.不同的二叉搜索树.md @@ -173,7 +173,6 @@ class Solution { //初始化0个节点和1个节点的情况 dp[0] = 1; dp[1] = 1; - //遍历 for (int i = 2; i <= n; i++) { for (int j = 1; j <= i; j++) { //对于第i个节点，需要考虑1作为根节点直到i作为根节点的情况，所以需要累加 From b38296b0da0b8233eccd74c2ba2a4fc5054da90a Mon Sep 17 00:00:00 2001 From: nanhuaibeian <49868746+nanhuaibeian@users.noreply.github.com> Date: Thu, 13 May 2021 09:50:19 +0800 Subject: [PATCH 11/13] =?UTF-8?q?=E6=B7=BB=E5=8A=A00131.=E5=88=86=E5=89=B2?= =?UTF-8?q?=E5=9B=9E=E6=96=87=E4=B8=B2=20Java=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0131.分割回文串.md | 39 ++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/problems/0131.分割回文串.md b/problems/0131.分割回文串.md index 01ff35c5..9c86a3bc 100644 --- a/problems/0131.分割回文串.md +++ b/problems/0131.分割回文串.md @@ -250,7 +250,46 @@ public: Java： +```Java +class Solution { + List> lists = new ArrayList<>(); + Deque deque = new LinkedList<>(); + public List> partition(String s) { + backTracking(s, 0); + return lists; + } + + private void backTracking(String s, int startIndex) { + //如果起始位置大于s的大小，说明找到了一组分割方案 + if (startIndex >= s.length()) { + lists.add(new ArrayList(deque)); + return; + } + for (int i = startIndex; i < s.length(); i++) { + //如果是回文子串，则记录 + if (isPalindrome(s, startIndex, i)) { + String str = s.substring(startIndex, i + 1); + deque.addLast(str); + } else { + continue; + } + //起始位置后移，保证不重复 + backTracking(s, i + 1); + deque.removeLast(); + } + } + //判断是否是回文串 + private boolean isPalindrome(String s, int startIndex, int end) { + for (int i = startIndex, j = end; i < j; i++, j--) { + if (s.charAt(i) != s.charAt(j)) { + return false; + } + } + return true; + } +} +``` Python： From 7dc72358924792a6ab8a5ac9f028f4da4a16e01f Mon Sep 17 00:00:00 2001 From: nanhuaibeian <49868746+nanhuaibeian@users.noreply.github.com> Date: Thu, 13 May 2021 09:51:51 +0800 Subject: [PATCH 12/13] =?UTF-8?q?=E6=B7=BB=E5=8A=A00020.=E6=9C=89=E6=95=88?= =?UTF-8?q?=E7=9A=84=E6=8B=AC=E5=8F=B7=20Java=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0020.有效的括号.md | 26 +++++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-) diff --git a/problems/0020.有效的括号.md b/problems/0020.有效的括号.md index f2d78ade..4dae7072 100644 --- a/problems/0020.有效的括号.md +++ b/problems/0020.有效的括号.md @@ -138,7 +138,31 @@ public: Java： - +```Java +class Solution { + public boolean isValid(String s) { + Deque deque = new LinkedList<>(); + char ch; + for (int i = 0; i < s.length(); i++) { + ch = s.charAt(i); + //碰到左括号，就把相应的右括号入栈 + if (ch == '(') { + deque.push(')'); + }else if (ch == '{') { + deque.push('}'); + }else if (ch == '[') { + deque.push(']'); + } else if (deque.isEmpty() || deque.peek() != ch) { + return false; + }else {//如果是右括号判断是否和栈顶元素匹配 + deque.pop(); + } + } + //最后判断栈中元素是否匹配 + return deque.isEmpty(); + } +} +``` Python： ```python3 From 20a518c856320d0faa53e12664120bef5ba8a53c Mon Sep 17 00:00:00 2001 From: nanhuaibeian <49868746+nanhuaibeian@users.noreply.github.com> Date: Thu, 13 May 2021 09:53:02 +0800 Subject: [PATCH 13/13] =?UTF-8?q?=E6=B7=BB=E5=8A=A00349.=E4=B8=A4=E4=B8=AA?= =?UTF-8?q?=E6=95=B0=E7=BB=84=E7=9A=84=E4=BA=A4=E9=9B=86=20Java=E7=89=88?= =?UTF-8?q?=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0349.两个数组的交集.md | 30 ++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/problems/0349.两个数组的交集.md b/problems/0349.两个数组的交集.md index c196b467..75ef9061 100644 --- a/problems/0349.两个数组的交集.md +++ b/problems/0349.两个数组的交集.md @@ -75,7 +75,37 @@ public: Java： +```Java +import java.util.HashSet; +import java.util.Set; +class Solution { + public int[] intersection(int[] nums1, int[] nums2) { + if (nums1 == null || nums1.length == 0 || nums2 == null || nums2.length == 0) { + return new int[0]; + } + Set set1 = new HashSet<>(); + Set resSet = new HashSet<>(); + //遍历数组1 + for (int i : nums1) { + set1.add(i); + } + //遍历数组2的过程中判断哈希表中是否存在该元素 + for (int i : nums2) { + if (set1.contains(i)) { + resSet.add(i); + } + } + int[] resArr = new int[resSet.size()]; + int index = 0; + //将结果几何转为数组 + for (int i : resSet) { + resArr[index++] = i; + } + return resArr; + } +} +``` Python：