Java

问题描述 https://leetcode.com/problems/maximum-subarray/#/description Find the contiguous subarray within an array (containing at least one number) which has the largest sum. For example, given the array [-2,1,-3,4,

问题描述 https://leetcode.com/problems/n-queens-ii/#/description Follow up for N-Queens problem. Now, instead outputting board configurations, return the total number of distinct solutions. 比N-Queens [http://www.zgljl2012.com/leetcode-51-n-queens/] 反倒容易一点了，因为不需要存储解法，只需要计算数目。

问题描述 https://leetcode.com/problems/n-queens/#/description The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other. Given an integer

问题描述 https://leetcode.com/problems/powx-n/#/description Implement pow(x, n). 实现pow(x,n)，及实现幂运算。 算法分析 这个题目的难度是中等，所以如果用显而易见的那个O(n)算法，即直接循环n次，将n个x乘起来的话是肯定会超时的，所以，只能用递归分治算法，即一次只乘一半，设值为A ，即当n为偶数时，结果是A*A；当n为奇数时，结果为A*A*x；

问题描述 https://leetcode.com/problems/anagrams/#/description Given an array of strings, group anagrams together. For example, given: ["eat", "tea", "tan", "ate", "nat", "bat"], Return: [ ["ate", "eat","tea"], ["nat","tan"], ["bat"] ] Note: All

问题描述 https://leetcode.com/problems/rotate-image/#/description You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Follow up: Could you do this in-place?

问题链接：https://leetcode.com/problems/permutations/#/description 求数组的全排列 算法 一个个的将每一个数插入数组，如数组[1,2,3]，设结果二重数组为r，初始化r中只有一个数组r=[[1]], 然后要插入数据2，有两种插法，[1,2]和[2,1]，即插在1前面和后面，从而r里有了两个数组r=[[1,2],[2,1]]，接下来插入数据3,对于数组 [1,

问题描述 https://leetcode.com/problems/multiply-strings/#/description Given two non-negative integers num1 and num2 represented as strings, return the product of num1 and num2. Note: * The length of both num1 and num2 is

问题描述 https://leetcode.com/problems/trapping-rain-water/#/description Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after

问题描述 https://leetcode.com/problems/first-missing-positive/#/description 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.

问题描述 Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each number in C may only be

问题描述 https://leetcode.com/problems/combination-sum/#/description Given a set of candidate numbers (C) (without duplicates) and a target number (T), find all unique combinations in C where the candidate numbers sums to