344. Reverse String Write a function that takes a string as input and returns the string reversed. Example: Given s = "hello", return "olleh". Subscribe to see which companies asked this question public class Solution { public String r…

题目:合并两个已排序链表 难度:Easy 题目内容: Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists. 翻译: 合并两个已排序的链表,并将其作为一个新链表返回.新的链表应该通过将前两个列表的节点拼接在一起. Example: Input: 1->2->4, 1-&…

100. Same Tree Total Accepted: 127501 Total Submissions: 294584 Difficulty: Easy Given two binary trees, write a function to check if they are equal or not. Two binary trees are considered equal if they are structurally identical and the nodes have t…

342. Power of Four Total Accepted: 7302 Total Submissions: 21876 Difficulty: Easy Given an integer (signed 32 bits), write a function to check whether it is a power of 4. Example: Given num = 16, return true. Given num = 5, return false. public class…

题目难度:Medium 题目: Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. Note: The solution set must not contain duplicate quadrup…

题目: Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution, and you may not use the same element twice. 翻译: 给定一组整数,两个数字的返回索引,它们的和会等于一个特定…

题目:求所有全排列 难度:Medium 题目内容: Given a collection of distinct integers, return all possible permutations. 翻译:给定一组各不相同的整数,返回所有可能的排列. Example: Input: [1,2,3] Output: [ [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], [3,2,1] ] 我的思路:每种情况中,每一个元素只出现一次,只是之间的顺序不同,那么…

题目: Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution, and you may not use the same element twice. 翻译: 给定一组整数,两个数字的返回索引,它们的和会等于一个特定…

题目:两整数相除 难度:Medium 题目内容: Given two integers dividend and divisor, divide two integers without using multiplication, division and mod operator. Return the quotient after dividing dividend by divisor. The integer division should truncate toward zero. 翻…

LeetCode:字符串的排列[567] 题目描述 给定两个字符串 s1 和 s2,写一个函数来判断 s2 是否包含 s1 的排列. 换句话说,第一个字符串的排列之一是第二个字符串的子串. 示例1: 输入: s1 = "ab" s2 = "eidbaooo" 输出: True 解释: s2 包含 s1 的排列之一 ("ba"). 示例2: 输入: s1= "ab" s2 = "eidboaoo" 输出: F…