原文链接: https://leetcode-cn.com/problems/sum-of-distances-in-tree 英文原文There is an undirected connected tree with n nodes labeled from 0 to n - 1 and n - 1 edges. You are given the integer n and the array edges where edges[i] = [ai, bi] indicates that t…

原文链接: https://leetcode-cn.com/problems/image-overlap 英文原文You are given two images, img1 and img2, represented as binary, square matrices of size n x n. A binary matrix has only 0s and 1s as values. We translate one image however we choose by sliding …

原文链接: https://leetcode-cn.com/problems/rectangle-overlap 英文原文An axis-aligned rectangle is represented as a list [x1, y1, x2, y2], where (x1, y1) is the coordinate of its bottom-left corner, and (x2, y2) is the coordinate of its top-right corner. Its …

原文链接: https://leetcode-cn.com/problems/new-21-game 英文原文Alice plays the following game, loosely based on the card game "21". Alice starts with 0 points and draws numbers while she has less than k points. During each draw, she gains an integer number o…

原文链接: https://leetcode-cn.com/problems/push-dominoes 英文原文There are n dominoes in a line, and we place each domino vertically upright. In the beginning, we simultaneously push some of the dominoes either to the left or to the right. After each second,…

原文链接: https://leetcode-cn.com/problems/similar-string-groups 英文原文Two strings X and Y are similar if we can swap two letters (in different positions) of X, so that it equals Y. Also two strings X and Y are similar if they are equal. For example, "tars…

原文链接: https://leetcode-cn.com/problems/keys-and-rooms 英文原文There are n rooms labeled from 0 to n - 1 and all the rooms are locked except for room 0. Your goal is to visit all the rooms. However, you cannot enter a locked room without having its key. W…

原文链接: https://leetcode-cn.com/problems/split-array-into-fibonacci-sequence 英文原文You are given a string of digits num, such as "123456579". We can split it into a Fibonacci-like sequence [123, 456, 579]. Formally, a Fibonacci-like sequence is a list f …

原文链接: https://leetcode-cn.com/problems/guess-the-word 英文原文This is an interactive problem. You are given an array of unique strings wordlist where wordlist[i] is 6 letters long, and one word in this list is chosen as secret. You may call Master.guess(…

原文链接: https://leetcode-cn.com/problems/backspace-string-compare 英文原文Given two strings s and t, return true if they are equal when both are typed into empty text editors. '#' means a backspace character. Note that after backspacing an empty text, the …

原文链接: https://leetcode-cn.com/problems/longest-mountain-in-array 英文原文You may recall that an array arr is a mountain array if and only if: arr.length >= 3 There exists some index i (0-indexed) with 0 < i < arr.length - 1 such that: arr[0] < arr[1] < .…

原文链接: https://leetcode-cn.com/problems/hand-of-straights 英文原文Alice has some number of cards and she wants to rearrange the cards into groups so that each group is of size groupSize, and consists of groupSize consecutive cards. Given an integer array …

原文链接: https://leetcode-cn.com/problems/shortest-path-visiting-all-nodes 英文原文You have an undirected, connected graph of n nodes labeled from 0 to n - 1. You are given an array graph where graph[i] is a list of all the nodes connected with node i by an…

原文链接: https://leetcode-cn.com/problems/shifting-letters 英文原文You are given a string s of lowercase English letters and an integer array shifts of the same length. Call the shift() of a letter, the next letter in the alphabet, (wrapping around so that …

原文链接: https://leetcode-cn.com/problems/rectangle-area-ii 英文原文You are given a 2D array of axis-aligned rectangles. Each rectangle[i] = [xi1, yi1, xi2, yi2] denotes the ith rectangle where (xi1, yi1) are the coordinates of the bottom-left corner, and (…

原文链接: https://leetcode-cn.com/problems/maximize-distance-to-closest-person 英文原文You are given an array representing a row of seats where seats[i] = 1 represents a person sitting in the ith seat, and seats[i] = 0 represents that the ith seat is empty (…

原文链接: https://leetcode-cn.com/problems/peak-index-in-a-mountain-array 英文原文Let's call an array arr a mountain if the following properties hold: arr.length >= 3 There exists some i with 0 < i < arr.length - 1 such that: arr[0] < arr[1] < ... arr[i-1] <…

原文链接: https://leetcode-cn.com/problems/car-fleet 英文原文There are n cars going to the same destination along a one-lane road. The destination is target miles away. You are given two integer array position and speed, both of length n, where position[i] i…

原文链接: https://leetcode-cn.com/problems/k-similar-strings 英文原文Strings s1 and s2 are k-similar (for some non-negative integer k) if we can swap the positions of two letters in s1 exactly k times so that the resulting string equals s2. Given two anagram…

原文链接: https://leetcode-cn.com/problems/exam-room 英文原文There is an exam room with n seats in a single row labeled from 0 to n - 1. When a student enters the room, they must sit in the seat that maximizes the distance to the closest person. If there are…

原文链接: https://leetcode-cn.com/problems/score-of-parentheses 英文原文Given a balanced parentheses string s, return the score of the string. The score of a balanced parentheses string is based on the following rule: "()" has score 1. AB has score A + B, wh…

原文链接: https://leetcode-cn.com/problems/minimum-cost-to-hire-k-workers 英文原文There are n workers. You are given two integer arrays quality and wage where quality[i] is the quality of the ith worker and wage[i] is the minimum wage expectation for the ith…

原文链接: https://leetcode-cn.com/problems/mirror-reflection 英文原文There is a special square room with mirrors on each of the four walls. Except for the southwest corner, there are receptors on each of the remaining corners, numbered 0, 1, and 2. The squar…

原文链接: https://leetcode-cn.com/problems/buddy-strings 英文原文Given two strings s and goal, return true if you can swap two letters in s so the result is equal to goal, otherwise, return false. Swapping letters is defined as taking two indices i and j (0-…

原文链接: https://leetcode-cn.com/problems/lemonade-change 英文原文At a lemonade stand, each lemonade costs $5. Customers are standing in a queue to buy from you, and order one at a time (in the order specified by bills). Each customer will only buy one lemo…

原文链接: https://leetcode-cn.com/problems/score-after-flipping-matrix 英文原文You are given an m x n binary matrix grid. A move consists of choosing any row or column and toggling each value in that row or column (i.e., changing all 0's to 1's, and all 1's …

原文链接: https://leetcode-cn.com/problems/all-nodes-distance-k-in-binary-tree 英文原文Given the root of a binary tree, the value of a target node target, and an integer k, return an array of the values of all nodes that have a distance k from the target nod…

原文链接: https://leetcode-cn.com/problems/random-pick-with-blacklist 英文原文You are given an integer n and an array of unique integers blacklist. Design an algorithm to pick a random integer in the range [0, n - 1] that is not in blacklist. Any integer tha…

原文链接: https://leetcode-cn.com/problems/shortest-path-to-get-all-keys 英文原文You are given an m x n grid grid where: '.' is an empty cell. '#' is a wall. '@' is the starting point. Lowercase letters represent keys. Uppercase letters represent locks. You …

原文链接: https://leetcode-cn.com/problems/smallest-subtree-with-all-the-deepest-nodes 英文原文Given the root of a binary tree, the depth of each node is the shortest distance to the root. Return the smallest subtree such that it contains all the deepest nod…