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Algorithem_ReverseLinkedListGiven the head of a singly linked list, reverse the list, and return the reversed list. Given the head of a singly linked list, reverse the list, and return the reversed list. Example 1: 12Input: head = [1,2,3,4,5]Output: [5,4,3,2,1] Example 2: 12Input: head = [1,2]Output: [2,1] Example 3: 12Input: head = []Output: [] Constraints: The number of nodes in the list is the range [0, 5000].-5000 <= Node.val <= 5000 Follow up: A linked list can be reversed e...

Algorithem_MergeTwoSortedListsYou are given the heads of two sorted linked lists list1 and list2. Merge the two lists in a one sorted list. The list should be made by splicing together the nodes of the first two lists. Return the head of the merged linked list. Example 1: 12Input: list1 = [1,2,4], list2 = [1,3,4]Output: [1,1,2,3,4,4] Example 2: 12Input: list1 = [], list2 = []Output: [] Example 3: 12Input: list1 = [], list2 = [0]Output: [0] 解法需求是合并两个有序的LinkList，所以解法是 判断 list1.val 和 list...

Algorithem_Merge Two Binary TreesYou are given two binary trees root1 and root2. Imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are not. You need to merge the two trees into a new binary tree. The merge rule is that if two nodes overlap, then sum node values up as the new value of the merged node. Otherwise, the NOT null node will be used as the node of the new tree. Return the merged tree. Note: The merging process must...

Algorithem_Populating Next Right Pointers in Each NodeYou are given a perfect binary tree where all leaves are on the same level, and every parent has two children. The binary tree has the following definition: 123456struct Node { int val; Node *left; Node *right; Node *next;} Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to NULL. Initially, all next pointers are set to NULL. Example 1: 12Input: root...

iOS长截图背景Twitter 上看到TaioApp的作者说，iOS 系统有支持长截图的API——UIScreenshotService，从 iOS 13开始就可以使用，下午的时候就在自己的 APP 中体验了一下。 过程UIScreenshotService官方的说明如下： When the user takes a screenshot of your app’s content, you work with a UIScreenshotService object to provide a PDF version of that screenshot. You do not create a UIScreenshotService object directly. Instead, you retrieve the object from the screenshotService property of your window scene and assign a delegate to it. When the user takes a screenshot, UI...

733. Algorithem_Max Area of IslandYou are given an m x n binary matrix grid. An island is a group of 1’s (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water. The area of an island is the number of cells with a value 1 in the island. Return the maximum area of an island in grid. If there is no island, return 0. Example 1: 123Input: grid = [[0,0,1,0,0,0,0,1,0,0,0,0,0],[0,0,0,0,0,0,0,1,1,1,0,0,0],[0,1,1,0,1,...

733. Flood FillAn image is represented by an m x n integer grid image where image[i][j] represents the pixel value of the image. You are also given three integers sr, sc, and newColor. You should perform a flood fill on the image starting from the pixel image[sr][sc]. To perform a flood fill, consider the starting pixel, plus any pixels connected 4-directionally to the starting pixel of the same color as the starting pixel, plus any pixels connected 4-directionally to those pixels (also wit...

Algorithem_Depth-First Search3. Longest Substring Without Repeating CharactersGiven a string s, find the length of the longest substring without repeating characters. Example 1: 123Input: s = "abcabcbb"Output: 3Explanation: The answer is "abc", with the length of 3. Example 2: 123Input: s = "bbbbb"Output: 1Explanation: The answer is "b", with the length of 1. Example 3: 1234Input: s = "pwwkew"Output: 3Explanation: The answer is "wke&q...

Algorithem_TwoPointersOfLinked List876. Middle of the Linked ListGiven the head of a singly linked list, return the middle node of the linked list. If there are two middle nodes, return the second middle node. Example 1: 123Input: head = [1,2,3,4,5]Output: [3,4,5]Explanation: The middle node of the list is node 3. Example 2: 123Input: head = [1,2,3,4,5,6]Output: [4,5,6]Explanation: Since the list has two middle nodes with values 3 and 4, we return the second one. 解法单看例子，感觉是获取数组中间位置到末尾，这个...

Algorithem_ReverseWordsReverse Words in a String IIIGiven a string s, reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order. Example 1: 12Input: s = "Let's take LeetCode contest"Output: "s'teL ekat edoCteeL tsetnoc" Example 2: 12Input: s = "God Ding"Output: "doG gniD" 解法一逻辑：把字符串根据空格切割成数组，然后遍历数组，对数组中字符串调用 reversed 方法，最后在使用空格join为字符串返回 代码如下： 12345678910111213class Solution &#...