Reverse digits of an integer. Example1: x = 123, return 321 Example2: x = -123, return -321Easy，没什么好说的注意负数和溢出的情况class Solution {public: int reverse(...

Given an unsorted integer array, find the first missing positive integer. For example, Given [1,2,0] return 3, and [3,4,-1,1] return 2. Your algorithm shou...

Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order. For example, Given n = 3,You should return the following mat...

The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens

Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:Integers in each row are sorted from left ...

Given an integer n, generate all structurally unique BST's (binary search trees) that store values 1...n. For example, Given n = 3, your program should retur...

Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array. Note: You may assume that nums1 has enough space (size that is g...

Evaluate the value of an arithmetic expression in Reverse Polish Notation. Valid operators are +, -, *, /. Each operand may be an integer or another expressi...

Given a list of non negative integers, arrange them such that they form the largest number. For example, given [3, 30, 34, 5, 9], the largest formed number is...

Given an integer n, return the number of trailing zeroes in n!. Note: Your solution should be in logarithmic time complexity. 求阶乘的后缀0个数 乘法中的零来源于10，10来源于2和5，......