题目:有效的数独表 难度:Medium 题目内容: Determine if a 9x9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules: Each row must contain the digits 1-9 without repetition. Each column must contain the digits 1-9 without…

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…

题目链接 题目要求: Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules. The Sudoku board could be partially filled, where empty cells are filled with the character '.'. A partially filled sudoku which is valid. Note: A valid Sudoku board…

Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules. The Sudoku board could be partially filled, where empty cells are filled with the character '.'. A partially filled sudoku which is valid. Note:A valid Sudoku board (partially…

题目: Write a program to solve a Sudoku puzzle by filling the empty cells. Empty cells are indicated by the character '.'. You may assume that there will be only one unique solution. A sudoku puzzle... ...and its solution numbers marked in red. 这题相对上题值…

题目:有效的括号序列 难度:Easy 题目内容: Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if: Open brackets must be closed by the same type of brackets. Open brackets must…

题目难度:hard 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)). Example 1: nums1 = [1, 3] nums2 = [2] The median is 2.0 Example 2: n…

题目:验证二叉搜索树 难度:Medium 题目内容: Given a binary tree, determine if it is a valid binary search tree (BST). Assume a BST is defined as follows: The left subtree of a node contains only nodes with keys less than the node's key. The right subtree of a node co…

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…

题目中文:求最长回文子串 题目难度:Medium 题目内容: Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000. 翻译: 给定一个字符串s,找出s中最长的回文子串.你可以假设s的最大长度是1000. 什么叫回文子串? 就是字符串中,满足能正读反读都一样的子串,就是回文子串.如下所示 Input: "babad"…

题目难度:hard 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)). Example 1: nums1 = [1, 3] nums2 = [2] The median is 2.0 Example 2: n…

Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring. For "(()", the longest valid parentheses substring is "()", which has length = 2. Another example is &…

题目难度:Medium 题目: 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: The solution set must not contain duplicate triplets. 翻译: 给定一个n个整数的数组S,S…

题目难度:Medium 题目: 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 exactly one solution. 翻译: 给定一个n个整数的数组S,在S…

题目难度:Medium 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). Find two lines, which together with x-axis form…

Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if: Open brackets must be closed by the same type of brackets. Open brackets must be closed in the correct…

题目:矩阵单词搜索 难度:Medium 题目内容: Given a 2D board and a word, find if the word exists in the grid. The word can be constructed from letters of sequentially adjacent cell, where "adjacent" cells are those horizontally or vertically neighboring. The same…

题目:矩阵置0 难度:Easy 题目内容:   Given a set of distinct integers, nums, return all possible subsets (the power set). Note: The solution set must not contain duplicate subsets. 翻译: 给定一组不同的整数,nums,返回所有可能的子集(包括空集和自身). 注意:解决方案集不能包含重复的子集. Example: Input: nums = […

题目:唯一路径(机器人走方格) 难度:Medium 题目内容: A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below). The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner o…

题目:通配符匹配 难度:hard 题目内容: Given an input string (s) and a pattern (p), implement wildcard pattern matching with support for '?' and '*'. '?' Matches any single character. '*' Matches any sequence of characters (including the empty sequence). The matchin…

题目:接雨水 难度:hard 题目内容: 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 raining. The above elevation map is represented by array [0,1,0,2,1,0,1,3,2,1,2,1]. In…

题目难度:Medium 题目: You are given two non-empty linked lists representing two non-negative integers. 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 linked list. You may assume…

题目难度:Easy 题目: Given a sorted array, remove the duplicates in-place such that each element appear only once and return the new length. Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extr…

题目难度:Medium 题目: 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 exactly one solution. 翻译: 给定一个n个整数的数组S,在S…

题目难度:Medium 题目: 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: The solution set must not contain duplicate triplets. 翻译: 给定一个n个整数的数组S,S…

题目难度:Medium 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). Find two lines, which together with x-axis form…

本题使用归并排序的思想,结合归并排序,写出的算法解. //数组中的逆序对 public static int InversePairs(int[] array){ if(array==null||array.length<=1) return 0; int[] copy = new int[array.length]; //复制原数组 copy = Arrays.copyOf(array, array.length); return mergeCount(array, copy, 0, arra…