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**LeetCode第10题 Regular Expression Matching **/*Given an input string (s) and a pattern (p), implement regular expression matching with support for '.' and '*''.' Matches any single character.'*' Matches zero or more of the preceding element.The matc

LeetCode第43题 Multiply Strings/*Given two non-negative integers num1 and num2 represented as strings, return the product of num1 and num2, also represented as a string.Note: You must not use any built-in BigInteger library or convert the inputs to integ

LeetCode第42题 Trapping Rain Water/*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

LeetCode第41题 First Missing Positive/*Given an unsorted integer array, find the smallest missing positive integer.Example 1:Input: [1,2,0] Output: 3 Example 2:Input: [3,4,-1,1] Output: 2 Example 3:Input: [7,8,9,11,12] Output: 1 Note:Y

LeetCode第39题 Combination Sum II/*Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where the candidate numbers sums to target.Each number in candidates may only be used once in

LeetCode第39题 Combination Sum/*Given a set of candidate numbers (candidates) (without duplicates) and a target number (target), find all unique combinations in candidates where the candidate numbers sums to target.The same repeated number may be chosen

LeetCode第38题 Count and Say/*The count-and-say sequence is the sequence of integers with the first five terms as following:1. 12. 113. 214. 12115. 1112211 is read off as "one 1"or 11.11 is read off as "two 1s"or 2121 is read off as "one 2, then

LeetCode第36题 Sudoku Solver/*Write a program to solve a Sudoku puzzle by filling the empty cells.A sudoku solution must satisfy all of the following rules: 1.Each of the digits 1-9 must occur exactly once in each row. 2.Each of the digits 1-9 must occ

LeetCode第36题 Valid Sudoku/*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 re

LeetCode第35题 Search Insert Position/*题目 #Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.You may assume no duplicates in the array.Example 1:In

LeetCode第34题 Find First and Last Position of Element in Sorted Array/*Given an array of integers mums sorted in ascending order, find the starting and ending position of a given target value.Your algorithm's runtime complexity must be in the order of O

LeetCode第33题 Search in Rotated Sorted Array/*Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.(i.e. [0, 1, 2, 4, 5, 6, 7] might become [4, 5,6, 7, 0, 1, 2]).You are given a target value to search. If found

LeetCode第32题 Longest Valid Parentheses/*Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring Example 1: Input: "(()"Output: 2Explanation: The longest valid parentheses sub

LeetCode第30题 Next Permutation/*Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.If such arrangement is not possible, it must rearrange it as the lowest possible order (ie, sorted in asc

LeetCode第30题/*You are given a string, s, and a list of words, words, that are all of the same length. Find all starting indices of substring(s) in s that is a concatenation of each word in words exactly once and without any intervening characters.Examp

LeetCode第29题/*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.Example 1:Inpu

LeetCode第28题/*Implement strStr().Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.Example 1:Input: haystack = "hello", needle = "ll"Output: 2Example 2:Input: haystack = "aaaaa", needle = "bba

LeetCode第27题/*Given an array nums and a value val, remove all instances of that value in-place 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) extra memory.The or

LeetCode第26题/*Given a sorted array nums, 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) ext

LeetCode第25题/*Given a linked list, reverse the nodes of a linked list k at a time and return its modified list.k is a positive integer and is less than or equal to the length of the linked list. If the number of nodes is not a multiple of k then left-o

LeetCode第24题class ListNode{ int val; ListNode next; ListNode(){}; ListNode(int val){this.val=val;} ListNode(int val, ListNode next) { this.val = val; this.next = next; }}public class SwapNodesPairs{ public static void main(String[] args){ ListN

LeetCode第23题/*Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.Example:Input:[ 1->4->5, 1->3->4, 2->6]Output: 1->1->2->3->4->4->5->6*/import java.util.*;

LeetCode第22题/*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:[ "((()))", "(()())", "(())()", "()(())", "()()()"]*/import java.util.*;cla

LeetCode第21题/*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.Example:Input: 1->2->4, 1->3->4Output: 1->1->2->3->4->4*/class Lis

LeetCode第20题/*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

LeetCode第19题/*Remove Nth Node From End of List #题目 #Given a linked list, remove the n-th node from the end of list and return its head.Example:Given linked list: 1->2->3->4->5, and n = 2.After removing the second node from the end, the

LeetCode第18题/*Given an array nums of n integers and an integer target, are there elements a, b, c, and d in nums 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 co

LeetCode第17题/*Given a string containing digits from 2-9 inclusive, 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. Note that 1 does not map to an

LeetCode第16题/*Given an array nums of n integers and an integer target, find three integers in nums such that the sum is closest to target. Return the sum of the three integers. You may assume that each input would have exactly one solution.Example:Giv

LeetCode第15题/*Given an array nums of n integers, are there elements a, b, c in nums 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.Example:Given a

LeetCode第13题/*Roman numerals are represented by seven different symbols: I(1), V(5), X(10), L(50), C(100), D(500) and M(1000).For example, two is written as II in Roman numeral, just two one's added together. Twelve is writen as, XII , which is simply

LeetCode第14题/*Write a function to find the longest common prefix string amongst an array of strings If there is no common prefix, return an empty string ""Example 1: Input: ["flower","flow","flight"]Output: "f1"Example 2: Input: ["dog", "racecar"

LeetCode第12题/*Roman numerals are represented by seven different symbols: I(1), V(5), X(10), L(50), C(100), D(500) and M(1000).For example, two is written as II in Roman numeral, just two one's added together. Twelve is written as, XII which is simply X

LeetCode第11题/*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 forms a

LeetCode第9题/*Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.Example 1:Input: 121Output: trueExample 2:Input: -121Output: falseExplanation: From left to right, it reads -121. Fr

LeetCode第8题/*Given an input string (s) and a pattern (p). 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 inp

LeetCode第8题/*Implement atoi which converts a string to an integer The function first discards as many whitespace characters as necessary until the first non-whitespace character is found. Then, starting from this character, takes an optional initial pl

LeetCode第7题/*Given a 32-bit signed integer, reverse digits of an integer.Example 1:Input: 123Output: 321Example 2:Input: -123Output: -321Example 3:Input: 120Output: 21Note: Assume we are dealing with an environment which could only store in

LeetCode第6题/*将一个给定字符串根据给定的行数，以从上往下、从左到右进行 Z 字形排列。比如输入字符串为 "LEETCODEISHIRING" 行数为 3 时，排列如下：L C I RE T O E S I I GE D H N之后，你的输出需要从左往右逐行读取，产生出一个新的字符串，比如："LCIRETOESIIGEDHN"。请你实现这个将字符串进行指定行数变换的函数：string convert(string s, int numRows);

上一篇博客问题解/*最长上升子序列（LIS）问题：给定长度为n的序列a，从a中抽取出一个子序列，这个子序列需要单调递增。问最长的上升子序列（LIS）的长度。　　e.g. 1,5,3,4,6,9,7,8的LIS为1,3,4,6,7,8，长度为6。*/import java.util.Arrays;public class Test02 { public static void main(String[] args){ // 最坏情况，数列是降序的，最长升序子序列长度为1