From e9c5f17af52cbeee408e349d7a7655b5d711bc80 Mon Sep 17 00:00:00 2001 From: posper Date: Thu, 29 Jul 2021 18:48:56 +0800 Subject: [PATCH 1/6] =?UTF-8?q?724.=E5=AF=BB=E6=89=BE=E6=95=B0=E7=BB=84?= =?UTF-8?q?=E7=9A=84=E4=B8=AD=E5=BF=83=E4=B8=8B=E6=A0=87=20=E6=B7=BB?= =?UTF-8?q?=E5=8A=A0Java=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0724.寻找数组的中心索引.md | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/problems/0724.寻找数组的中心索引.md b/problems/0724.寻找数组的中心索引.md index bf989979..09966e05 100644 --- a/problems/0724.寻找数组的中心索引.md +++ b/problems/0724.寻找数组的中心索引.md @@ -67,6 +67,24 @@ public: ## Java ```java +class Solution { + public int pivotIndex(int[] nums) { + int sum = 0; + for (int i = 0; i < nums.length; i++) { + sum += nums[i]; // 总和 + } + int leftSum = 0; + int rightSum = 0; + for (int i = 0; i < nums.length; i++) { + leftSum += nums[i]; + rightSum = sum - leftSum + nums[i]; // leftSum 里面已经有 nums[i]，多减了一次，所以加上 + if (leftSum == rightSum) { + return i; + } + } + return -1; // 不存在 + } +} ``` ## Python @@ -90,4 +108,3 @@ public: * 知识星球：[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ)
- From 3fd951ef5fec91b3dc9be7e57aa76daf83c35f87 Mon Sep 17 00:00:00 2001 From: posper Date: Thu, 29 Jul 2021 18:56:15 +0800 Subject: [PATCH 2/6] =?UTF-8?q?922.=20=E6=8C=89=E5=A5=87=E5=81=B6=E6=8E=92?= =?UTF-8?q?=E5=BA=8F=E6=95=B0=E7=BB=84II=20=E6=B7=BB=E5=8A=A0Java=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/0922.按奇偶排序数组II.md | 26 +++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-) diff --git a/problems/0922.按奇偶排序数组II.md b/problems/0922.按奇偶排序数组II.md index bb609c12..d4c1be7a 100644 --- a/problems/0922.按奇偶排序数组II.md +++ b/problems/0922.按奇偶排序数组II.md @@ -120,6 +120,31 @@ public: ## Java ```java +// 方法一 +class Solution { + public int[] sortArrayByParityII(int[] nums) { + // 分别存放 nums 中的奇数、偶数 + int len = nums.length; + int evenIndex = 0; + int oddIndex = 0; + int[] even = new int[len / 2]; + int[] odd = new int[len / 2]; + for (int i = 0; i < len; i++) { + if (nums[i] % 2 == 0) { + even[evenIndex++] = nums[i]; + } else { + odd[oddIndex++] = nums[i]; + } + } + // 把奇偶数组重新存回 nums + int index = 0; + for (int i = 0; i < even.length; i++) { + nums[index++] = even[i]; + nums[index++] = odd[i]; + } + return nums; + } +} ``` ## Python @@ -143,4 +168,3 @@ public: * 知识星球：[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ)
- From d8247fe8499f14497972fc32456f752a7bf6d574 Mon Sep 17 00:00:00 2001 From: posper Date: Thu, 29 Jul 2021 19:22:47 +0800 Subject: [PATCH 3/6] =?UTF-8?q?844.=E6=AF=94=E8=BE=83=E5=90=AB=E9=80=80?= =?UTF-8?q?=E6=A0=BC=E7=9A=84=E5=AD=97=E7=AC=A6=E4=B8=B2=20=E6=B7=BB?= =?UTF-8?q?=E5=8A=A0Java=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0844.比较含退格的字符串.md | 28 +++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) diff --git a/problems/0844.比较含退格的字符串.md b/problems/0844.比较含退格的字符串.md index 9f37959d..4b4ff63b 100644 --- a/problems/0844.比较含退格的字符串.md +++ b/problems/0844.比较含退格的字符串.md @@ -14,7 +14,7 @@ 给定 S 和 T 两个字符串，当它们分别被输入到空白的文本编辑器后，判断二者是否相等，并返回结果。 # 代表退格字符。 注意：如果对空文本输入退格字符，文本继续为空。 -  + 示例 1： * 输入：S = "ab#c", T = "ad#c" * 输出：true @@ -160,6 +160,32 @@ public: Java： +```java +// 普通方法（使用栈的思路） +class Solution { + public boolean backspaceCompare(String s, String t) { + StringBuilder ssb = new StringBuilder(); // 模拟栈 + StringBuilder tsb = new StringBuilder(); // 模拟栈 + // 分别处理两个 String + for (char c : s.toCharArray()) { + if (c != '#') { + ssb.append(c); // 模拟入栈 + } else if (ssb.length() > 0){ // 栈非空才能弹栈 + ssb.deleteCharAt(ssb.length() - 1); // 模拟弹栈 + } + } + for (char c : t.toCharArray()) { + if (c != '#') { + tsb.append(c); // 模拟入栈 + } else if (tsb.length() > 0){ // 栈非空才能弹栈 + tsb.deleteCharAt(tsb.length() - 1); // 模拟弹栈 + } + } + return ssb.toString().equals(tsb.toString()); + } +} +``` + Python： Go： From a6a8650b8a6524ed03cf599f1c32fc42c78cd8e5 Mon Sep 17 00:00:00 2001 From: posper Date: Thu, 29 Jul 2021 19:32:33 +0800 Subject: [PATCH 4/6] =?UTF-8?q?205.=E5=90=8C=E6=9E=84=E5=AD=97=E7=AC=A6?= =?UTF-8?q?=E4=B8=B2=20=E6=B7=BB=E5=8A=A0Java=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0205.同构字符串.md | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/problems/0205.同构字符串.md b/problems/0205.同构字符串.md index 4e963ece..06ea5701 100644 --- a/problems/0205.同构字符串.md +++ b/problems/0205.同构字符串.md @@ -68,6 +68,25 @@ public: ## Java ```java +class Solution { + public boolean isIsomorphic(String s, String t) { + Map map1 = new HashMap<>(); + Map map2 = new HashMap<>(); + for (int i = 0, j = 0; i < s.length(); i++, j++) { + if (!map1.containsKey(s.charAt(i))) { + map1.put(s.charAt(i), t.charAt(j)); // map1保存 s[i] 到 t[j]的映射 + } + if (!map2.containsKey(t.charAt(j))) { + map2.put(t.charAt(j), s.charAt(i)); // map1保存 t[j] 到 s[i]的映射 + } + // 无法映射，返回 false + if (map1.get(s.charAt(i)) != t.charAt(j) || map2.get(t.charAt(j)) != s.charAt(i)) { + return false; + } + } + return true; + } +} ``` ## Python From 9e08c0e5de17773b345f0cc59fb661b333bd946f Mon Sep 17 00:00:00 2001 From: posper Date: Thu, 29 Jul 2021 19:36:37 +0800 Subject: [PATCH 5/6] =?UTF-8?q?205.=E5=90=8C=E6=9E=84=E5=AD=97=E7=AC=A6?= =?UTF-8?q?=E4=B8=B2=20=E6=B7=BB=E5=8A=A0Java=E7=89=88=E6=9C=AC=EF=BC=88?= =?UTF-8?q?=E6=B3=A8=E9=87=8A=E4=BF=AE=E6=94=B9=EF=BC=89?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0205.同构字符串.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/0205.同构字符串.md b/problems/0205.同构字符串.md index 06ea5701..7ffa3fbf 100644 --- a/problems/0205.同构字符串.md +++ b/problems/0205.同构字符串.md @@ -77,7 +77,7 @@ class Solution { map1.put(s.charAt(i), t.charAt(j)); // map1保存 s[i] 到 t[j]的映射 } if (!map2.containsKey(t.charAt(j))) { - map2.put(t.charAt(j), s.charAt(i)); // map1保存 t[j] 到 s[i]的映射 + map2.put(t.charAt(j), s.charAt(i)); // map2保存 t[j] 到 s[i]的映射 } // 无法映射，返回 false if (map1.get(s.charAt(i)) != t.charAt(j) || map2.get(t.charAt(j)) != s.charAt(i)) { From 1521e4016537243bd2a6d5898f2099e53f588d42 Mon Sep 17 00:00:00 2001 From: posper Date: Thu, 29 Jul 2021 20:00:16 +0800 Subject: [PATCH 6/6] =?UTF-8?q?31.=E4=B8=8B=E4=B8=80=E4=B8=AA=E6=8E=92?= =?UTF-8?q?=E5=88=97=20=E6=B7=BB=E5=8A=A0Java=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0031.下一个排列.md | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/problems/0031.下一个排列.md b/problems/0031.下一个排列.md index fbe31eb3..53e6644d 100644 --- a/problems/0031.下一个排列.md +++ b/problems/0031.下一个排列.md @@ -99,6 +99,24 @@ public: ## Java ```java +class Solution { + public void nextPermutation(int[] nums) { + for (int i = nums.length - 1; i >= 0; i--) { + for (int j = nums.length - 1; j > i; j--) { + if (nums[j] > nums[i]) { + // 交换 + int temp = nums[i]; + nums[i] = nums[j]; + nums[j] = temp; + // [i + 1, nums.length) 内元素升序排序 + Arrays.sort(nums, i + 1, nums.length); + return; + } + } + } + Arrays.sort(nums); // 不存在下一个更大的排列，则将数字重新排列成最小的排列（即升序排列）。 + } +} ``` ## Python