原文链接: https://leetcode-cn.com/problems/find-duplicate-subtrees 英文原文Given the root of a binary tree, return all duplicate subtrees. For each kind of duplicate subtrees, you only need to return the root node of any one of them. Two trees are duplicate …

原文链接: https://leetcode-cn.com/problems/two-sum-iv-input-is-a-bst 英文原文Given the root of a Binary Search Tree and a target number k, return true if there exist two elements in the BST such that their sum is equal to the given target. Example 1: Input: …

原文链接: https://leetcode-cn.com/problems/maximum-binary-tree 英文原文You are given an integer array nums with no duplicates. A maximum binary tree can be built recursively from nums using the following algorithm: Create a root node whose value is the maxim…

原文链接: https://leetcode-cn.com/problems/print-binary-tree 英文原文Given the root of a binary tree, construct a 0-indexed m x n string matrix res that represents a formatted layout of the tree. The formatted layout matrix should be constructed using the fo…

原文链接: https://leetcode-cn.com/problems/robot-return-to-origin 英文原文There is a robot starting at the position (0, 0), the origin, on a 2D plane. Given a sequence of its moves, judge if this robot ends up at (0, 0) after it completes its moves. You are …

原文链接: https://leetcode-cn.com/problems/find-k-closest-elements 英文原文Given a sorted integer array arr, two integers k and x, return the k closest integers to x in the array. The result should also be sorted in ascending order. An integer a is closer to…

原文链接: https://leetcode-cn.com/problems/split-array-into-consecutive-subsequences 英文原文You are given an integer array nums that is sorted in non-decreasing order. Determine if it is possible to split nums into one or more subsequences such that both of…

原文链接: https://leetcode-cn.com/problems/image-smoother 英文原文An image smoother is a filter of the size 3 x 3 that can be applied to each cell of an image by rounding down the average of the cell and the eight surrounding cells (i.e., the average of the …

原文链接: https://leetcode-cn.com/problems/maximum-width-of-binary-tree 英文原文Given the root of a binary tree, return the maximum width of the given tree. The maximum width of a tree is the maximum width among all levels. The width of one level is defined …

原文链接: https://leetcode-cn.com/problems/strange-printer 英文原文There is a strange printer with the following two special properties: The printer can only print a sequence of the same character each time. At each turn, the printer can print new characters…

原文链接: https://leetcode-cn.com/problems/non-decreasing-array 英文原文Given an array nums with n integers, your task is to check if it could become non-decreasing by modifying at most one element. We define an array is non-decreasing if nums[i] <= nums[i +…

原文链接: https://leetcode-cn.com/problems/beautiful-arrangement-ii 英文原文Given two integers n and k, construct a list answer that contains n different positive integers ranging from 1 to n and obeys the following requirement: Suppose this list is answer =…

原文链接: https://leetcode-cn.com/problems/kth-smallest-number-in-multiplication-table 英文原文Nearly everyone has used the Multiplication Table. The multiplication table of size m x n is an integer matrix mat where mat[i][j] == i * j (1-indexed). Given thre…

原文链接: https://leetcode-cn.com/problems/trim-a-binary-search-tree 英文原文Given the root of a binary search tree and the lowest and highest boundaries as low and high, trim the tree so that all its elements lies in [low, high]. Trimming the tree should no…

原文链接: https://leetcode-cn.com/problems/maximum-swap 英文原文You are given an integer num. You can swap two digits at most once to get the maximum valued number. Return the maximum valued number you can get. Example 1: Input: num = 2736 Output: 7236 Expla…

原文链接: https://leetcode-cn.com/problems/bulb-switcher-ii 英文原文There is a room with n bulbs labeled from 1 to n that all are turned on initially, and four buttons on the wall. Each of the four buttons has a different functionality where: Button 1: Flips…

原文链接: https://leetcode-cn.com/problems/number-of-longest-increasing-subsequence 英文原文Given an integer array nums, return the number of longest increasing subsequences. Notice that the sequence has to be strictly increasing. Example 1: Input: nums = [1…

原文链接: https://leetcode-cn.com/problems/cut-off-trees-for-golf-event 英文原文You are asked to cut off all the trees in a forest for a golf event. The forest is represented as an m x n matrix. In this matrix: 0 means the cell cannot be walked through. 1 re…

原文链接: https://leetcode-cn.com/problems/longest-continuous-increasing-subsequence 英文原文Given an unsorted array of integers nums, return the length of the longest continuous increasing subsequence (i.e. subarray). The subsequence must be strictly increa…

原文链接: https://leetcode-cn.com/problems/implement-magic-dictionary 英文原文Design a data structure that is initialized with a list of different words. Provided a string, you should determine if you can change exactly one character in this string to match …

原文链接: https://leetcode-cn.com/problems/map-sum-pairs 英文原文Design a map that allows you to do the following: Maps a string key to a given value. Returns the sum of the values that have a key with a prefix equal to a given string. Implement the MapSum c…

原文链接: https://leetcode-cn.com/problems/valid-parenthesis-string 英文原文Given a string s containing only three types of characters: '(', ')' and '*', return true if s is valid. The following rules define a valid string: Any left parenthesis '(' must have…

原文链接: https://leetcode-cn.com/problems/24-game 英文原文You are given an integer array cards of length 4. You have four cards, each containing a number in the range [1, 9]. You should arrange the numbers on these cards in a mathematical expression using t…

原文链接: https://leetcode-cn.com/problems/valid-palindrome-ii 英文原文Given a string s, return true if the s can be palindrome after deleting at most one character from it. Example 1: Input: s = "aba" Output: true Example 2: Input: s = "abca" Output: true E…

原文链接: https://leetcode-cn.com/problems/redundant-connection 英文原文In this problem, a tree is an undirected graph that is connected and has no cycles. You are given a graph that started as a tree with n nodes labeled from 1 to n, with one additional edg…

原文链接: https://leetcode-cn.com/problems/redundant-connection-ii 英文原文In this problem, a rooted tree is a directed graph such that, there is exactly one node (the root) for which all other nodes are descendants of this node, plus every node has exactly …

原文链接: https://leetcode-cn.com/problems/repeated-string-match 英文原文Given two strings a and b, return the minimum number of times you should repeat string a so that string b is a substring of it. If it is impossible for b​​​​​​ to be a substring of a af…

原文链接: https://leetcode-cn.com/problems/longest-univalue-path 英文原文Given the root of a binary tree, return the length of the longest path, where each node in the path has the same value. This path may or may not pass through the root. The length of the…

原文链接: https://leetcode-cn.com/problems/knight-probability-in-chessboard 英文原文On an n x n chessboard, a knight starts at the cell (row, column) and attempts to make exactly k moves. The rows and columns are 0-indexed, so the top-left cell is (0, 0), an…

原文链接: https://leetcode-cn.com/problems/maximum-sum-of-3-non-overlapping-subarrays 英文原文Given an integer array nums and an integer k, find three non-overlapping subarrays of length k with maximum sum and return them. Return the result as a list of indi…