原文链接: https://leetcode-cn.com/problems/bulb-switcher-iii 英文原文There is a room with n bulbs, numbered from 1 to n, arranged in a row from left to right. Initially, all the bulbs are turned off. At moment k (for k from 0 to n - 1), we turn on the light[…

原文链接: https://leetcode-cn.com/problems/time-needed-to-inform-all-employees 英文原文A company has n employees with a unique ID for each employee from 0 to n - 1. The head of the company is the one with headID. Each employee has one direct manager given in…

原文链接: https://leetcode-cn.com/problems/frog-position-after-t-seconds 英文原文Given an undirected tree consisting of n vertices numbered from 1 to n. A frog starts jumping from vertex 1. In one second, the frog jumps from its current vertex to another unv…

原文链接: https://leetcode-cn.com/problems/lucky-numbers-in-a-matrix 英文原文Given an m x n matrix of distinct numbers, return all lucky numbers in the matrix in any order. A lucky number is an element of the matrix such that it is the minimum element in its…

原文链接: https://leetcode-cn.com/problems/design-a-stack-with-increment-operation 英文原文Design a stack which supports the following operations. Implement the CustomStack class: CustomStack(int maxSize) Initializes the object with maxSize which is the maxi…

原文链接: https://leetcode-cn.com/problems/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree 英文原文Given two binary trees original and cloned and given a reference to a node target in the original tree. The cloned tree is a copy of the ori…

原文链接: https://leetcode-cn.com/problems/maximum-performance-of-a-team 英文原文You are given two integers n and k and two integer arrays speed and efficiency both of length n. There are n engineers numbered from 1 to n. speed[i] and efficiency[i] represent…

原文链接: https://leetcode-cn.com/problems/count-largest-group 英文原文Given an integer n. Each number from 1 to n is grouped according to the sum of its digits. Return how many groups have the largest size. Example 1: Input: n = 13 Output: 4 Explanation: Th…

原文链接: https://leetcode-cn.com/problems/circle-and-rectangle-overlapping 英文原文Given a circle represented as (radius, x_center, y_center) and an axis-aligned rectangle represented as (x1, y1, x2, y2), where (x1, y1) are the coordinates of the bottom-lef…

原文链接: https://leetcode-cn.com/problems/construct-k-palindrome-strings 英文原文Given a string s and an integer k. You should construct k non-empty palindrome strings using all the characters in s. Return True if you can use all the characters in s to cons…

原文链接: https://leetcode-cn.com/problems/reducing-dishes 英文原文A chef has collected data on the satisfaction level of his n dishes. Chef can cook any dish in 1 unit of time. Like-time coefficient of a dish is defined as the time taken to cook that dish i…

原文链接: https://leetcode-cn.com/problems/check-if-there-is-a-valid-path-in-a-grid 英文原文Given a m x n grid. Each cell of the grid represents a street. The street of grid[i][j] can be: 1 which means a street connecting the left cell and the right cell. 2 …

原文链接: https://leetcode-cn.com/problems/longest-happy-prefix 英文原文A string is called a happy prefix if is a non-empty prefix which is also a suffix (excluding itself). Given a string s, return the longest happy prefix of s. Return an empty string "" if…

原文链接: https://leetcode-cn.com/problems/find-lucky-integer-in-an-array 英文原文Given an array of integers arr, a lucky integer is an integer which has a frequency in the array equal to its value. Return a lucky integer in the array. If there are multiple …

原文链接: https://leetcode-cn.com/problems/count-number-of-teams 英文原文There are n soldiers standing in a line. Each soldier is assigned a unique rating value. You have to form a team of 3 soldiers amongst them under the following rules: Choose 3 soldiers …

原文链接: https://leetcode-cn.com/problems/design-underground-system 英文原文An underground railway system is keeping track of customer travel times between different stations. They are using this data to calculate the average time it takes to travel from on…

原文链接: https://leetcode-cn.com/problems/find-all-good-strings 英文原文Given the strings s1 and s2 of size n and the string evil, return the number of good strings. A good string has size n, it is alphabetically greater than or equal to s1, it is alphabeti…

原文链接: https://leetcode-cn.com/problems/minimum-value-to-get-positive-step-by-step-sum 英文原文Given an array of integers nums, you start with an initial positive value startValue. In each iteration, you calculate the step by step sum of startValue plus e…

原文链接: https://leetcode-cn.com/problems/find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k 英文原文Given an integer k, return the minimum number of Fibonacci numbers whose sum is equal to k. The same Fibonacci number can be used multiple times. T…

原文链接: https://leetcode-cn.com/problems/the-k-th-lexicographical-string-of-all-happy-strings-of-length-n 英文原文A happy string is a string that: consists only of letters of the set ['a', 'b', 'c']. s[i] != s[i + 1] for all values of i from 1 to s.length …

原文链接: https://leetcode-cn.com/problems/minimum-subsequence-in-non-increasing-order 英文原文Given the array nums, obtain a subsequence of the array whose sum of elements is strictly greater than the sum of the non included elements in such subsequence. If…

原文链接: https://leetcode-cn.com/problems/number-of-steps-to-reduce-a-number-in-binary-representation-to-one 英文原文Given the binary representation of an integer as a string s, return the number of steps to reduce it to 1 under the following rules: If the …

原文链接: https://leetcode-cn.com/problems/stone-game-iii 英文原文Alice and Bob continue their games with piles of stones. There are several stones arranged in a row, and each stone has an associated value which is an integer given in the array stoneValue. A…

原文链接: https://leetcode-cn.com/problems/string-matching-in-an-array 英文原文Given an array of string words. Return all strings in words which is substring of another word in any order. String words[i] is substring of words[j], if can be obtained removing …

原文链接: https://leetcode-cn.com/problems/queries-on-a-permutation-with-key 英文原文Given the array queries of positive integers between 1 and m, you have to process all queries[i] (from i=0 to i=queries.length-1) according to the following rules: In the be…

原文链接: https://leetcode-cn.com/problems/html-entity-parser 英文原文HTML entity parser is the parser that takes HTML code as input and replace all the entities of the special characters by the characters itself. The special characters and their entities fo…

原文链接: https://leetcode-cn.com/problems/number-of-ways-to-paint-n-3-grid 英文原文You have a grid of size n x 3 and you want to paint each cell of the grid with exactly one of the three colors: Red, Yellow, or Green while making sure that no two adjacent c…

原文链接: https://leetcode-cn.com/problems/kids-with-the-greatest-number-of-candies 英文原文There are n kids with candies. You are given an integer array candies, where each candies[i] represents the number of candies the ith kid has, and an integer extraCan…

原文链接: https://leetcode-cn.com/problems/check-if-a-string-can-break-another-string 英文原文Given two strings: s1 and s2 with the same size, check if some permutation of string s1 can break some permutation of string s2 or vice-versa. In other words s2 can…

原文链接: https://leetcode-cn.com/problems/number-of-ways-to-wear-different-hats-to-each-other 英文原文There are n people and 40 types of hats labeled from 1 to 40. Given a list of list of integers hats, where hats[i] is a list of all hats preferred by the i…