From 7b785ab004eaa2635980a96ee543cbe65f4852de Mon Sep 17 00:00:00 2001 From: Steve2020 <841532108@qq.com> Date: Thu, 13 Jan 2022 22:14:12 +0800 Subject: [PATCH 1/9] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=EF=BC=880383.=E8=B5=8E?= =?UTF-8?q?=E9=87=91=E4=BF=A1.md=EF=BC=89=EF=BC=9A=E5=A2=9E=E5=8A=A0typesc?= =?UTF-8?q?ript=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0383.赎金信.md | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/problems/0383.赎金信.md b/problems/0383.赎金信.md index 650f2a99..31e19b10 100644 --- a/problems/0383.赎金信.md +++ b/problems/0383.赎金信.md @@ -264,6 +264,27 @@ var canConstruct = function(ransomNote, magazine) { }; ``` +TypeScript: + +```typescript +function canConstruct(ransomNote: string, magazine: string): boolean { + let helperArr: number[] = new Array(26).fill(0); + let base: number = 'a'.charCodeAt(0); + let index: number; + for (let i = 0, length = magazine.length; i < length; i++) { + helperArr[magazine[i].charCodeAt(0) - base]++; + } + for (let i = 0, length = ransomNote.length; i < length; i++) { + index = ransomNote[i].charCodeAt(0) - base; + helperArr[index]--; + if (helperArr[index] < 0) { + return false; + } + } + return true; +}; +``` + PHP: ```php From 9d59aab89e5a61f752e67f3c969260a98a95fded Mon Sep 17 00:00:00 2001 From: bqlin Date: Mon, 20 Dec 2021 18:26:34 +0800 Subject: [PATCH 2/9] =?UTF-8?q?0028.=E5=AE=9E=E7=8E=B0strStr=EF=BC=9A?= =?UTF-8?q?=E4=BC=98=E5=8C=96=E6=8E=92=E7=89=88?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0028.实现strStr.md | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/problems/0028.实现strStr.md b/problems/0028.实现strStr.md index f0b56719..c23f5558 100644 --- a/problems/0028.实现strStr.md +++ b/problems/0028.实现strStr.md @@ -259,7 +259,7 @@ void getNext(int* next, const string& s) 然后还要对next数组进行初始化赋值，如下： -``` +```cpp int j = -1; next[0] = j; ``` @@ -278,8 +278,8 @@ next[i] 表示 i（包括i）之前最长相等的前后缀长度（其实就是 所以遍历模式串s的循环下标i 要从 1开始，代码如下： -``` -for(int i = 1; i < s.size(); i++) { +```cpp +for (int i = 1; i < s.size(); i++) { ``` 如果 s[i] 与 s[j+1]不相同，也就是遇到 前后缀末尾不相同的情况，就要向前回退。 @@ -292,7 +292,7 @@ next[j]就是记录着j（包括j）之前的子串的相同前后缀的长度 所以，处理前后缀不相同的情况代码如下： -``` +```cpp while (j >= 0 && s[i] != s[j + 1]) { // 前后缀不相同了     j = next[j]; // 向前回退 } @@ -300,7 +300,7 @@ while (j >= 0 && s[i] != s[j + 1]) { // 前后缀不相同了 3. 处理前后缀相同的情况 -如果s[i] 与 s[j + 1] 相同，那么就同时向后移动i 和j 说明找到了相同的前后缀，同时还要将j（前缀的长度）赋给next[i], 因为next[i]要记录相同前后缀的长度。 +如果 s[i] 与 s[j + 1] 相同，那么就同时向后移动i 和j 说明找到了相同的前后缀，同时还要将j（前缀的长度）赋给next[i], 因为next[i]要记录相同前后缀的长度。 代码如下： @@ -346,7 +346,7 @@ void getNext(int* next, const string& s){ i就从0开始，遍历文本串，代码如下： -``` +```cpp for (int i = 0; i < s.size(); i++)  ``` @@ -356,7 +356,7 @@ for (int i = 0; i < s.size(); i++)  代码如下： -``` +```cpp while(j >= 0 && s[i] != t[j + 1]) {     j = next[j]; } @@ -364,7 +364,7 @@ while(j >= 0 && s[i] != t[j + 1]) { 如果 s[i] 与 t[j + 1] 相同，那么i 和 j 同时向后移动， 代码如下： -``` +```cpp if (s[i] == t[j + 1]) {     j++; // i的增加在for循环里 } @@ -376,7 +376,7 @@ if (s[i] == t[j + 1]) { 代码如下： -``` +```cpp if (j == (t.size() - 1) ) {     return (i - t.size() + 1); } From 57af6f6a4b8941e5422c8387ab8591501c5f28f4 Mon Sep 17 00:00:00 2001 From: bqlin Date: Mon, 20 Dec 2021 19:53:51 +0800 Subject: [PATCH 3/9] =?UTF-8?q?0027.=E7=A7=BB=E9=99=A4=E5=85=83=E7=B4=A0?= =?UTF-8?q?=EF=BC=9A=E4=BC=98=E5=8C=96=E6=8E=92=E7=89=88?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0027.移除元素.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/0027.移除元素.md b/problems/0027.移除元素.md index 99990302..d69f2bcf 100644 --- a/problems/0027.移除元素.md +++ b/problems/0027.移除元素.md @@ -42,7 +42,7 @@ ![27.移除元素-暴力解法](https://tva1.sinaimg.cn/large/008eGmZEly1gntrc7x9tjg30du09m1ky.gif) -很明显暴力解法的时间复杂度是O(n^2)，这道题目暴力解法在leetcode上是可以过的。 +很明显暴力解法的时间复杂度是$O(n^2)$，这道题目暴力解法在leetcode上是可以过的。 代码如下： From 71ada4737a7cc00de5403c43f73a7d6c824eb7b2 Mon Sep 17 00:00:00 2001 From: bqlin Date: Mon, 20 Dec 2021 19:54:34 +0800 Subject: [PATCH 4/9] =?UTF-8?q?=E6=A0=88=E4=B8=8E=E9=98=9F=E5=88=97?= =?UTF-8?q?=E7=90=86=E8=AE=BA=E5=9F=BA=E7=A1=80=EF=BC=9A=E4=BC=98=E5=8C=96?= =?UTF-8?q?=E6=8E=92=E7=89=88?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/栈与队列理论基础.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/problems/栈与队列理论基础.md b/problems/栈与队列理论基础.md index b9811b29..44fcbdd5 100644 --- a/problems/栈与队列理论基础.md +++ b/problems/栈与队列理论基础.md @@ -67,7 +67,7 @@ deque是一个双向队列，只要封住一段，只开通另一端就可以实 我们也可以指定vector为栈的底层实现，初始化语句如下： -``` +```cpp std::stack > third; // 使用vector为底层容器的栈 ``` @@ -77,7 +77,7 @@ std::stack > third; // 使用vector为底层容器的栈 也可以指定list 为起底层实现，初始化queue的语句如下： -``` +```cpp std::queue> third; // 定义以list为底层容器的队列 ``` From 13601e89abdff1a8b196645f647db551d8f4154e Mon Sep 17 00:00:00 2001 From: bqlin Date: Mon, 20 Dec 2021 20:13:03 +0800 Subject: [PATCH 5/9] =?UTF-8?q?0225.=E7=94=A8=E9=98=9F=E5=88=97=E5=AE=9E?= =?UTF-8?q?=E7=8E=B0=E6=A0=88=E3=80=810232.=E7=94=A8=E6=A0=88=E5=AE=9E?= =?UTF-8?q?=E7=8E=B0=E9=98=9F=E5=88=97=EF=BC=9A=E4=BC=98=E5=8C=96=E6=8E=92?= =?UTF-8?q?=E7=89=88?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0225.用队列实现栈.md | 2 +- problems/0232.用栈实现队列.md | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/problems/0225.用队列实现栈.md b/problems/0225.用队列实现栈.md index fdb544a6..524ca329 100644 --- a/problems/0225.用队列实现栈.md +++ b/problems/0225.用队列实现栈.md @@ -46,7 +46,7 @@ 模拟的队列执行语句如下： -``` +```cpp queue.push(1); queue.push(2); queue.pop(); // 注意弹出的操作 diff --git a/problems/0232.用栈实现队列.md b/problems/0232.用栈实现队列.md index 4edba2f2..0e4fce28 100644 --- a/problems/0232.用栈实现队列.md +++ b/problems/0232.用栈实现队列.md @@ -21,7 +21,7 @@ empty() -- 返回队列是否为空。 示例: -``` +```cpp MyQueue queue = new MyQueue(); queue.push(1); queue.push(2); From cd4529c8ff7c4570a4541988c1cf3a76e3586150 Mon Sep 17 00:00:00 2001 From: bin3826246 <59920177+bin3826246@users.noreply.github.com> Date: Fri, 14 Jan 2022 19:15:00 +0800 Subject: [PATCH 6/9] =?UTF-8?q?Create=20=E9=9D=A2=E8=AF=95=E9=A2=98=2002.0?= =?UTF-8?q?7.=20=E8=A7=A3=E6=B3=95=E6=9B=B4=E6=96=B0.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/面试题 02.07. 解法更新.md | 41 +++++++++++++++++++++++ 1 file changed, 41 insertions(+) create mode 100644 problems/面试题 02.07. 解法更新.md diff --git a/problems/面试题 02.07. 解法更新.md b/problems/面试题 02.07. 解法更新.md new file mode 100644 index 00000000..119f875c --- /dev/null +++ b/problems/面试题 02.07. 解法更新.md @@ -0,0 +1,41 @@ +# 双指针，不计算链表长度 +设置指向headA和headB的指针pa、pb，分别遍历两个链表，每次循环同时更新pa和pb。 +* 当链表A遍历完之后，即pa为空时，将pa指向headB； +* 当链表B遍历完之后，即pa为空时，将pb指向headA； +* 当pa与pb相等时，即指向同一个节点，该节点即为相交起始节点。 +* 若链表不相交，则pa、pb同时为空时退出循环，即如果链表不相交，pa与pb在遍历过全部节点后同时指向结尾空节点，此时退出循环，返回空。 +# 证明思路 +设链表A不相交部分长度为a，链表B不相交部分长度为b，两个链表相交部分长度为c。
+在pa指向链表A时，即pa为空之前，pa经过链表A不相交部分和相交部分，走过的长度为a+c；
+pa指向链表B后，在移动相交节点之前经过链表B不相交部分，走过的长度为b，总合为a+c+b。
+同理，pb走过长度的总合为b+c+a。二者相等，即pa与pb可同时到达相交起始节点。
+该方法可避免计算具体链表长度。 +```cpp +class Solution { +public: + ListNode *getIntersectionNode(ListNode *headA, ListNode *headB) { + //链表为空时，返回空指针 + if(headA == nullptr || headB == nullptr) return nullptr; + ListNode* pa = headA; + ListNode* pb = headB; + //pa与pb在遍历过全部节点后,同时指向结尾空节点时退出循环 + while(pa != nullptr || pb != nullptr){ + //pa为空时，将pa指向headB + if(pa == nullptr){ + pa = headB; + } + //pa为空时，将pb指向headA + if(pb == nullptr){ + pb = headA; + } + //pa == pb时，返回相交起始节点 + if(pa == pb){ + return pa; + } + pa = pa->next; + pb = pb->next; + } + return nullptr; + } +}; +``` From 570022f6666b633891bb9e590488529d5238d254 Mon Sep 17 00:00:00 2001 From: bin3826246 <59920177+bin3826246@users.noreply.github.com> Date: Fri, 14 Jan 2022 19:20:36 +0800 Subject: [PATCH 7/9] =?UTF-8?q?=E9=9D=A2=E8=AF=95=E9=A2=9802.07=20?= =?UTF-8?q?=E6=B7=BB=E5=8A=A0cpp=E5=8F=8C=E6=8C=87=E9=92=88=E6=96=B0?= =?UTF-8?q?=E8=A7=A3=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 双指针新解法，不需计算链表长度 --- problems/面试题 02.07. 解法更新.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/面试题 02.07. 解法更新.md b/problems/面试题 02.07. 解法更新.md index 119f875c..6115d02e 100644 --- a/problems/面试题 02.07. 解法更新.md +++ b/problems/面试题 02.07. 解法更新.md @@ -28,7 +28,7 @@ public: if(pb == nullptr){ pb = headA; } - //pa == pb时，返回相交起始节点 + //pa与pb相等时，返回相交起始节点 if(pa == pb){ return pa; } From 2ea72e3e4345e0de2feed93b4a74dd9bbbc25b68 Mon Sep 17 00:00:00 2001 From: Steve2020 <841532108@qq.com> Date: Fri, 14 Jan 2022 21:59:34 +0800 Subject: [PATCH 8/9] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=EF=BC=880015.=E4=B8=89?= =?UTF-8?q?=E6=95=B0=E4=B9=8B=E5=92=8C.md=EF=BC=89=EF=BC=9A=E5=A2=9E?= =?UTF-8?q?=E5=8A=A0typescript=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0015.三数之和.md | 36 +++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/problems/0015.三数之和.md b/problems/0015.三数之和.md index c78ab06d..8992c5f4 100644 --- a/problems/0015.三数之和.md +++ b/problems/0015.三数之和.md @@ -332,7 +332,43 @@ var threeSum = function(nums) { return res; }; ``` +TypeScript: +```typescript +function threeSum(nums: number[]): number[][] { + nums.sort((a, b) => a - b); + let length = nums.length; + let left: number = 0, + right: number = length - 1; + let resArr: number[][] = []; + for (let i = 0; i < length; i++) { + if (i > 0 && nums[i] === nums[i - 1]) { + continue; + } + left = i + 1; + right = length - 1; + while (left < right) { + let total: number = nums[i] + nums[left] + nums[right]; + if (total === 0) { + resArr.push([nums[i], nums[left], nums[right]]); + left++; + right--; + while (nums[right] === nums[right + 1]) { + right--; + } + while (nums[left] === nums[left - 1]) { + left++; + } + } else if (total < 0) { + left++; + } else { + right--; + } + } + } + return resArr; +}; +``` ruby: ```ruby From 12bf8ae05b176816a21cfd741b2274bfada14aae Mon Sep 17 00:00:00 2001 From: Steve2020 <841532108@qq.com> Date: Fri, 14 Jan 2022 22:36:55 +0800 Subject: [PATCH 9/9] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=EF=BC=880018.=E5=9B=9B?= =?UTF-8?q?=E6=95=B0=E4=B9=8B=E5=92=8C.md=EF=BC=89=EF=BC=9A=E5=A2=9E?= =?UTF-8?q?=E5=8A=A0typescript=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0018.四数之和.md | 42 +++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/problems/0018.四数之和.md b/problems/0018.四数之和.md index b94ebeef..dae8636b 100644 --- a/problems/0018.四数之和.md +++ b/problems/0018.四数之和.md @@ -311,7 +311,49 @@ var fourSum = function(nums, target) { }; ``` +TypeScript： + +```typescript +function fourSum(nums: number[], target: number): number[][] { + nums.sort((a, b) => a - b); + let first: number = 0, + second: number, + third: number, + fourth: number; + let length: number = nums.length; + let resArr: number[][] = []; + for (; first < length; first++) { + if (first > 0 && nums[first] === nums[first - 1]) { + continue; + } + for (second = first + 1; second < length; second++) { + if ((second - first) > 1 && nums[second] === nums[second - 1]) { + continue; + } + third = second + 1; + fourth = length - 1; + while (third < fourth) { + let total: number = nums[first] + nums[second] + nums[third] + nums[fourth]; + if (total === target) { + resArr.push([nums[first], nums[second], nums[third], nums[fourth]]); + third++; + fourth--; + while (nums[third] === nums[third - 1]) third++; + while (nums[fourth] === nums[fourth + 1]) fourth--; + } else if (total < target) { + third++; + } else { + fourth--; + } + } + } + } + return resArr; +}; +``` + PHP: + ```php class Solution { /**