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There are two sorted arrays nums1 and nums2 of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)).一、题目描述给定两个大小分别为m和n的

Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters for "abcabcbb" is "abc", which the length is 3. Fo

Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring.一、题目描述求最长回文子

The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)P A H NA P L S I

Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exa

Reverse digits of an integer.Example1: x = 123, return 321Example2: x = -123, return -321click to show spoilers.Have you thought about this?Here are some good questions to ask before c

Given an array of integers, find two numbers such that they add up to a specific target number.The function twoSum should return indices of the two numbers such that they add up to the target, whe

Implement atoi to convert a string to an integer.Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input ca

Given a digit string, return all possible letter combinations that the number could represent.A mapping of digit to letters (just like on the telephone buttons) is given below.Input:Digi

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:

Determine whether an integer is a palindrome. Do this without extra space.判断一个整数是否为回文，解决思路很简单，就是不断取整数的第一位和最后一位进行比较，相等则继续取第二位和倒数第二位，直到整数的所有位都比较完成或者中途找到了不一致的位。#include#includeusing namespace std;

Implement regular expression matching with support for '.' and '*'.'.' Matches any single character.'*' Matches zero or more of the preceding element.The matching should cover the entire input

Given n non-negative integers a1, a2, ..., an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of line i is at (i, ai) and (i, 0). Fin

Given a linked list, remove the nth node from the end of list and return its head.For example,Given linked list: 1->2->3->4->5, and n = 2. After removing the second node from the end, th

Given an integer, convert it to a roman numeral.Input is guaranteed to be within the range from 1 to 3999.#include#include#includeusing namespace std;class Solution {public: string int

Given a roman numeral, convert it to an integer.Input is guaranteed to be within the range from 1 to 3999.#include#include#include#includeusing namespace std;class Solution {public: in

You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a link

Write a function to find the longest common prefix string amongst an array of strings.要求找出字符串数组中所有字符串的最长公共前缀。解题思路：两个字符串的最长公共前缀，其长度肯定不会超过最短的字符串的长度，设最短的字符串长度为m，那么只要比较这两个字符串的前m个字符即可。每次得出两个字符串的最长公共前

Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity./*** Definition for singly-linked list.* struct ListNode {* int val;* ListNode *next;

Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.The brackets must close in the correct order, "()" and "()[]{}" are all va

Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined betw

You are climbing a stair case. It takes n steps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?//设f(n)表示爬n阶楼梯的不同方法，有两种选择：/

Reverse a singly linked list.一、题目描述 翻转单链表二、解题思路利用两个结点指针和一个中间结点指针temp(用来记录当前结点的下一个节点的位置)，分别指向当前结点和前一个结点，每次循环让当前结点的指针域指向前一个结点即可，翻转结束后，记得将最后一个节点的链域置为空。class Solution {public: List

Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.Note:Elements in a triplet (a,b,c

Write a function that takes an unsigned integer and returns the number of ’1' bits it has (also known as the Hamming weight).For example, the 32-bit integer ’11' has binary representation 000000

Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times.You may assume that the array is non-empty and the majority element

Given a sorted linked list, delete all duplicates such that each element appear only once.For example,Given 1->1->2, return 1->2.Given 1->1->2->3->3, return 1->2->3.Subscribe to see wh

Write a program to check whether a given number is an ugly number.Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 6, 8 are ugly while 14 is not ugly sinc

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.For example, given n = 3, a solution set is:"((()))", "(()())", "(())()", "()(())", "

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.//Definition for singly-linked list. struct ListNo

Given a linked list, swap every two adjacent nodes and return its head.For example,Given 1->2->3->4, you should return the list as 2->1->4->3.Your algorithm should use only constant space. Y

Two elements of a binary search tree (BST) are swapped by mistake.Recover the tree without changing its structure.Note:A solution using O(n) space is pretty straight forward. Could you devis

Given a binary tree, find its minimum depth.The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.//递归方法求二叉树的最小深度 //注意判断树的深度应该到叶子节点

Write an algorithm to determine if a number 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 squares

Implement the following operations of a queue using stacks.push(x) -- Push element x to the back of queue.pop() -- Removes the element from in front of queue.peek() -- Get the front element.em

Given an integer, write a function to determine if it is a power of two.//题目要求：求一个数是否是2的幂次方//解题方法：//方法一：如果某个值是2的幂次方所得，其对应二进制则是最高位为1，其余位为0.//n-1则相反，除了最高位，其余比特位均为1,则我们可以判断n&(n-1)是否等于0来判断n是否是2的幂

Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.For example:Given the below binary tree and sum = 22, 5 / \

Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root).For example:Given binary tree {3,9,20,#,#,15,7},

Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).For example:Given binary tree {3,9,20,#,#,15,7}, 3 / \ 9 20

Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string.If the last word does not exist, return 0.Note: A word is