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一.问题描述ZigZagConversion: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 legibi

一.问题描述Given a sorted array of integers, find the starting and ending position of a given target value.Your algorithm's runtime complexity must be in the order of O(log n).If the target i

一.问题描述Implement pow(x, n).实现指数乘法。二.代码编写首先想到的其实就是把n不断拆分成n/2，但是想歪了，可能沉浸在大数乘法那个题里，然后发现其实小数乘大数比两个相等的数运算复杂度低一点，所以就否定了这个想法。但看了tags是二分的思想，后来一想其实重点不在于每次运算的复杂度，而在于二分能将运算的次数由O(N)降低到O(logN)。所以其实这

一.问题描述Given a set of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.The same repeated number may be chosen from C un

一.问题描述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.For example, Given [0,1,0,2,1,0,

一、问题描述Given a collection of intervals, merge all overlapping intervals.For example,Given [1,3],[2,6],[8,10],[15,18],return [1,6],[8,10],[15,18]二、代码编写    这个算法思想很简单，只要将list按照interval的s

一.问题描述给定一组integers，找出其中最小的缺失的正整数值，要求时间复杂度为O(n)，空间复杂度为O(1)。二.代码编写时间复杂度为O(n)意味着不能直接对list进行排序O(NlogN)，空间复杂度为常数意味着不能新建一个list。常数空间，我们应该想到直接swap，将相应得到数字m放到list的(m-1)的位置上。全部交换完毕后，返回list中第一个不满

一.问题描述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 n, return all distinct solutions to the n-que

一.问题描述实现字符串的乘法，不能直接将字符串转化成int哦~二.代码编写首先想到的方法就是根据我们平时手算乘法的方法来计算，本质上就是移位相乘相加~但是时间复杂度是O(N^2)。代码如下：'''@ author: wttttt at 2016.10.29@ problem description see: https://leetcode.com/prob

一.问题描述Implement wildcard pattern matching with support for '?' and '*'.'?' Matches any single character.'*' Matches any sequence of characters (including the empty sequence).The matching sh

一.问题描述Given an array of non-negative integers, you are initially positioned at the first index of the array.Each element in the array represents your maximum jump length at that position.

一、问题描述The set [1,2,3,…,n] contains a total of n! unique permutations.By listing and labeling all of the permutations in order,We get the following sequence (ie, for n = 3):"123""132"

一、问题描述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

问题描述Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place.代码编写*很明显是遍历的思想，但是做不到一遍做完所有，至少要两遍。 *于是想到先遍历行，再遍历列。为节省时间，在遍历列的时候，需要置零的列就不再考虑已经被置零的行。 *我的思路问题就在于只考虑了优化时间复

一.问题描述Suppose a sorted array 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 in the

一.问题描述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

一.题目描述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:[ "((()))", "(()())", "(())()

一.问题描述Palindrome Number Determine whether an integer is a palindrome. Do thiswithout extra space.spoilers:Some hints:Could negative integers be palindromes? (ie, -1)If

一.问题描述Longest Palindromic SubstringGiven 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 pal

一.问题描述Two Sum: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.

一.问题描述Longest Substring Without Repeating Characters Given a string, find the length of the longest substring without repeating characters.Examples:Given "abcabcbb", the answer is 

一.问题描述Median of Two Sorted Arrays 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 complexi

一.问题描述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 (

一.问题描述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 ent

一.问题描述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

一.问题描述Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.合并k条有序链表，返回一条有序链表二.算法思想有两种思路：1）利用二路归并的思想，将k条有序链条两两进行二路归并，一共需要logk次合并后得到最终链表。显然

一.问题描述Given an array and a value, remove all instances of that valuein place and return the new length.Do not allocate extra space for another array, you must do this in place with constan

一.问题描述Implement strStr().Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.二.代码编写    最基本的想法就是，为两个字符串指定两个指针，相同则两个指针后移，不同则子串回退到0，母串往前

一.问题描述        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.        #合并两个有序链表，当然要求结果也是有序链表#Defini

36题：一.问题描述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 '.'.

一.问题描述Divide two integers without using multiplication, division and mod operator.If it is overflow, return MAX_INT.实现两个int的除法，代码中不能使用乘、除和取余操作，溢出时返回max_int。二.代码编写    最基