原文链接: https://leetcode-cn.com/problems/reverse-pairs 英文原文Given an integer array nums, return the number of reverse pairs in the array. A reverse pair is a pair (i, j) where 0 <= i < j < nums.length and nums[i] > 2 * nums[j]. Example 1: Input: nums = …

原文链接: https://leetcode-cn.com/problems/target-sum 英文原文You are given an integer array nums and an integer target. You want to build an expression out of nums by adding one of the symbols '+' and '-' before each integer in nums and then concatenate all…

原文链接: https://leetcode-cn.com/problems/teemo-attacking 英文原文Our hero Teemo is attacking an enemy Ashe with poison attacks! When Teemo attacks Ashe, Ashe gets poisoned for a exactly duration seconds. More formally, an attack at second t will mean Ashe …

原文链接: https://leetcode-cn.com/problems/next-greater-element-i 英文原文The next greater element of some element x in an array is the first greater element that is to the right of x in the same array. You are given two distinct 0-indexed integer arrays num…

原文链接: https://leetcode-cn.com/problems/diagonal-traverse 英文原文Given an m x n matrix mat, return an array of all the elements of the array in a diagonal order. Example 1: Input: mat = [[1,2,3],[4,5,6],[7,8,9]] Output: [1,2,4,7,5,3,6,8,9] Example 2: Inp…

原文链接: https://leetcode-cn.com/problems/keyboard-row 英文原文Given an array of strings words, return the words that can be typed using letters of the alphabet on only one row of American keyboard like the image below. In the American keyboard: the first r…

原文链接: https://leetcode-cn.com/problems/find-mode-in-binary-search-tree 英文原文Given the root of a binary search tree (BST) with duplicates, return all the mode(s) (i.e., the most frequently occurred element) in it. If the tree has more than one mode, re…

原文链接: https://leetcode-cn.com/problems/ipo 英文原文Suppose LeetCode will start its IPO soon. In order to sell a good price of its shares to Venture Capital, LeetCode would like to work on some projects to increase its capital before the IPO. Since it has…

原文链接: https://leetcode-cn.com/problems/next-greater-element-ii 英文原文Given a circular integer array nums (i.e., the next element of nums[nums.length - 1] is nums[0]), return the next greater number for every element in nums. The next greater number of …

原文链接: https://leetcode-cn.com/problems/base-7 英文原文Given an integer num, return a string of its base 7 representation. Example 1: Input: num = 100 Output: "202" Example 2: Input: num = -7 Output: "-10" Constraints: -107 <= num <= 107 中文题目给定一个整数 num，将其…

原文链接: https://leetcode-cn.com/problems/relative-ranks 英文原文You are given an integer array score of size n, where score[i] is the score of the ith athlete in a competition. All the scores are guaranteed to be unique. The athletes are placed based on th…

原文链接: https://leetcode-cn.com/problems/perfect-number 英文原文A perfect number is a positive integer that is equal to the sum of its positive divisors, excluding the number itself. A divisor of an integer x is an integer that can divide x evenly. Given a…

原文链接: https://leetcode-cn.com/problems/most-frequent-subtree-sum 英文原文Given the root of a binary tree, return the most frequent subtree sum. If there is a tie, return all the values with the highest frequency in any order. The subtree sum of a node is…

原文链接: https://leetcode-cn.com/problems/find-bottom-left-tree-value 英文原文Given the root of a binary tree, return the leftmost value in the last row of the tree. Example 1: Input: root = [2,1,3] Output: 1 Example 2: Input: root = [1,2,3,4,null,5,6,null,…

原文链接: https://leetcode-cn.com/problems/freedom-trail 英文原文In the video game Fallout 4, the quest "Road to Freedom" requires players to reach a metal dial called the "Freedom Trail Ring" and use the dial to spell a specific keyword to open the door. Gi…

原文链接: https://leetcode-cn.com/problems/find-largest-value-in-each-tree-row 英文原文Given the root of a binary tree, return an array of the largest value in each row of the tree (0-indexed). Example 1: Input: root = [1,3,2,5,3,null,9] Output: [1,3,9] Exam…

原文链接: https://leetcode-cn.com/problems/longest-palindromic-subsequence 英文原文Given a string s, find the longest palindromic subsequence's length in s. A subsequence is a sequence that can be derived from another sequence by deleting some or no elements…

原文链接: https://leetcode-cn.com/problems/super-washing-machines 英文原文You have n super washing machines on a line. Initially, each washing machine has some dresses or is empty. For each move, you could choose any m (1 <= m <= n) washing machines, and pas…

原文链接: https://leetcode-cn.com/problems/coin-change-2 英文原文You are given an integer array coins representing coins of different denominations and an integer amount representing a total amount of money. Return the number of combinations that make up tha…

原文链接: https://leetcode-cn.com/problems/detect-capital 英文原文We define the usage of capitals in a word to be right when one of the following cases holds: All letters in this word are capitals, like "USA". All letters in this word are not capitals, like …

原文链接: https://leetcode-cn.com/problems/longest-uncommon-subsequence-ii 英文原文Given an array of strings strs, return the length of the longest uncommon subsequence between them. If the longest uncommon subsequence does not exist, return -1. An uncommon …

原文链接: https://leetcode-cn.com/problems/continuous-subarray-sum 英文原文Given an integer array nums and an integer k, return true if nums has a continuous subarray of size at least two whose elements sum up to a multiple of k, or false otherwise. An integ…

原文链接: https://leetcode-cn.com/problems/longest-word-in-dictionary-through-deleting 英文原文Given a string s and a string array dictionary, return the longest string in the dictionary that can be formed by deleting some of the given string characters. If …

原文链接: https://leetcode-cn.com/problems/contiguous-array 英文原文Given a binary array nums, return the maximum length of a contiguous subarray with an equal number of 0 and 1. Example 1: Input: nums = [0,1] Output: 2 Explanation: [0, 1] is the longest con…

原文链接: https://leetcode-cn.com/problems/beautiful-arrangement 英文原文Suppose you have n integers labeled 1 through n. A permutation of those n integers perm (1-indexed) is considered a beautiful arrangement if for every i (1 <= i <= n), either of the fol…

原文链接: https://leetcode-cn.com/problems/swapping-nodes-in-a-linked-list 英文原文You are given the head of a linked list, and an integer k. Return the head of the linked list after swapping the values of the kth node from the beginning and the kth node fro…

原文链接: https://leetcode-cn.com/problems/minesweeper 英文原文Let's play the minesweeper game (Wikipedia, online game)! You are given an m x n char matrix board representing the game board where: 'M' represents an unrevealed mine, 'E' represents an unreveal…

原文链接: https://leetcode-cn.com/problems/minimum-absolute-difference-in-bst 英文原文Given the root of a Binary Search Tree (BST), return the minimum absolute difference between the values of any two different nodes in the tree. Example 1: Input: root = [4,…

原文链接: https://leetcode-cn.com/problems/encode-and-decode-tinyurl 英文原文Note: This is a companion problem to the System Design problem: Design TinyURL. TinyURL is a URL shortening service where you enter a URL such as https://leetcode.com/problems/desig…

原文链接: https://leetcode-cn.com/problems/complex-number-multiplication 英文原文A complex number can be represented as a string on the form "real+imaginaryi" where: real is the real part and is an integer in the range [-100, 100]. imaginary is the imaginary…