原文链接: https://leetcode-cn.com/problems/duplicate-emails 英文原文Table: Person +-------------+---------+ | Column Name | Type | +-------------+---------+ | id | int | | email | varchar | +-------------+---------+ id is the primary key column for this tabl…

原文链接: https://leetcode-cn.com/problems/customers-who-never-order 英文原文Table: Customers +-------------+---------+ | Column Name | Type | +-------------+---------+ | id | int | | name | varchar | +-------------+---------+ id is the primary key column fo…

原文链接: https://leetcode-cn.com/problems/department-top-three-salaries 英文原文Table: Employee +--------------+---------+ | Column Name | Type | +--------------+---------+ | id | int | | name | varchar | | salary | int | | departmentId | int | +-----------…

原文链接: https://leetcode-cn.com/problems/department-highest-salary 英文原文Table: Employee +--------------+---------+ | Column Name | Type | +--------------+---------+ | id | int | | name | varchar | | salary | int | | departmentId | int | +--------------+…

原文链接: https://leetcode-cn.com/problems/repeated-dna-sequences 英文原文The DNA sequence is composed of a series of nucleotides abbreviated as 'A', 'C', 'G', and 'T'. For example, "ACGAATTCCG" is a DNA sequence. When studying DNA, it is useful to identify …

原文链接: https://leetcode-cn.com/problems/best-time-to-buy-and-sell-stock-iv 英文原文You are given an integer array prices where prices[i] is the price of a given stock on the ith day, and an integer k. Find the maximum profit you can achieve. You may compl…

原文链接: https://leetcode-cn.com/problems/rotate-array 英文原文Given an array, rotate the array to the right by k steps, where k is non-negative. Example 1: Input: nums = [1,2,3,4,5,6,7], k = 3 Output: [5,6,7,1,2,3,4] Explanation: rotate 1 steps to the righ…

原文链接: https://leetcode-cn.com/problems/reverse-bits 英文原文Reverse bits of a given 32 bits unsigned integer. Note: Note that in some languages, such as Java, there is no unsigned integer type. In this case, both input and output will be given as a signe…

原文链接: https://leetcode-cn.com/problems/number-of-1-bits 英文原文Write a function that takes an unsigned integer and returns the number of '1' bits it has (also known as the Hamming weight). Note: Note that in some languages, such as Java, there is no uns…

原文链接: https://leetcode-cn.com/problems/valid-phone-numbers 英文原文Given a text file file.txt that contains a list of phone numbers (one per line), write a one-liner bash script to print all valid phone numbers. You may assume that a valid phone number m…

原文链接: https://leetcode-cn.com/problems/transpose-file 英文原文Given a text file file.txt, transpose its content. You may assume that each row has the same number of columns, and each field is separated by the ' ' character. Example: If file.txt has the f…

原文链接: https://leetcode-cn.com/problems/tenth-line 英文原文Given a text file file.txt, print just the 10th line of the file. Example: Assume that file.txt has the following content: Line 1 Line 2 Line 3 Line 4 Line 5 Line 6 Line 7 Line 8 Line 9 Line 10 Yo…

原文链接: https://leetcode-cn.com/problems/delete-duplicate-emails 英文原文Table: Person +-------------+---------+ | Column Name | Type | +-------------+---------+ | id | int | | email | varchar | +-------------+---------+ id is the primary key column for th…

原文链接: https://leetcode-cn.com/problems/rising-temperature 英文原文Table: Weather +---------------+---------+ | Column Name | Type | +---------------+---------+ | id | int | | recordDate | date | | temperature | int | +---------------+---------+ id is the…

原文链接: https://leetcode-cn.com/problems/house-robber 英文原文You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent…

原文链接: https://leetcode-cn.com/problems/binary-tree-right-side-view 英文原文Given the root of a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom. Example 1: Input: root =…

原文链接: https://leetcode-cn.com/problems/number-of-islands 英文原文Given an m x n 2D binary grid grid which represents a map of '1's (land) and '0's (water), return the number of islands. An island is surrounded by water and is formed by connecting adjacen…

原文链接: https://leetcode-cn.com/problems/bitwise-and-of-numbers-range 英文原文Given two integers left and right that represent the range [left, right], return the bitwise AND of all numbers in this range, inclusive. Example 1: Input: left = 5, right = 7 Ou…

原文链接: https://leetcode-cn.com/problems/happy-number 英文原文Write an algorithm to determine if a number n is happy. A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squa…

原文链接: https://leetcode-cn.com/problems/count-primes 英文原文Given an integer n, return the number of prime numbers that are strictly less than n. Example 1: Input: n = 10 Output: 4 Explanation: There are 4 prime numbers less than 10, they are 2, 3, 5, 7.…

原文链接: https://leetcode-cn.com/problems/isomorphic-strings 英文原文Given two strings s and t, determine if they are isomorphic. Two strings s and t are isomorphic if the characters in s can be replaced to get t. All occurrences of a character must be repl…

原文链接: https://leetcode-cn.com/problems/reverse-linked-list 英文原文Given the head of a singly linked list, reverse the list, and return the reversed list. Example 1: Input: head = [1,2,3,4,5] Output: [5,4,3,2,1] Example 2: Input: head = [1,2] Output: [2,…

原文链接: https://leetcode-cn.com/problems/course-schedule 英文原文There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1. You are given an array prerequisites where prerequisites[i] = [ai, bi] indicates that you must take…

原文链接: https://leetcode-cn.com/problems/implement-trie-prefix-tree 英文原文A trie (pronounced as "try") or prefix tree is a tree data structure used to efficiently store and retrieve keys in a dataset of strings. There are various applications of this dat…

原文链接: https://leetcode-cn.com/problems/minimum-size-subarray-sum 英文原文Given an array of positive integers nums and a positive integer target, return the minimal length of a contiguous subarray [numsl, numsl+1, ..., numsr-1, numsr] of which the sum is …

原文链接: https://leetcode-cn.com/problems/course-schedule-ii 英文原文There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1. You are given an array prerequisites where prerequisites[i] = [ai, bi] indicates that you must t…

原文链接: https://leetcode-cn.com/problems/design-add-and-search-words-data-structure 英文原文Design a data structure that supports adding new words and finding if a string matches any previously added string. Implement the WordDictionary class: WordDictiona…

原文链接: https://leetcode-cn.com/problems/word-search-ii 英文原文Given an m x n board of characters and a list of strings words, return all words on the board. Each word must be constructed from letters of sequentially adjacent cells, where adjacent cells a…

原文链接: https://leetcode-cn.com/problems/house-robber-ii 英文原文You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed. All houses at this place are arranged in a circle. That means the first …

原文链接: https://leetcode-cn.com/problems/kth-largest-element-in-an-array 英文原文Given an integer array nums and an integer k, return the kth largest element in the array. Note that it is the kth largest element in the sorted order, not the kth distinct el…