基本知识  最近博主在刷Leedcode题，很多人都是采用位运算来解题的，看的我满脸雾水，所以上网收集了一下c++中关于位运算的知识，为此总结一下，有不妥的地方还望指正。  

12summap结构存储每个数的下标，每遍历一个nums[i]，找出map中target-nums[i]对应的下标，即返回i和该下标。2AddTwoNumbers两个链表表示两个倒序的整数，相加后得一整数并倒序形成链表。就是把两个链表从头结点开始相加，注意进位3LongestSubstringWithoutRepeatingCharacters用vector初始化每个字符出现的位置为-1，如若重复

题目：Givenalinkedlist,determineifithasacycleinit.Givenalinkedlist,returnthenodewherethecyclebegins.Ifthereisnocycle,returnnull.思路：链表有环判断：设置快慢指针，如果快慢指针相遇，则证明有环。（1）设置快慢指针，因为链表中有环，所以最终会相遇，相遇点为C（2）两个指针分别放在链

1、MedianofTwoSortedArrays——这是leedcode的第四题：Therearetwosortedarraysnums1andnums2ofsizemandnrespectively.Findthemedianofthetwosortedarrays.TheoverallruntimecomplexityshouldbeO

1、LongestSubstringWithoutRepeatingCharacters——这是leedcode的第三题：Givenastring,findthelengthofthelongestsubstringwithoutrepeatingcharacters.Examples

1、ZigZagConversion——这是leedcode的第六题：Thestring“PAYPALISHIRING”iswritteninazigzagpatternonagivennumberofrowslikethis

1、AddTwoNumbers——这是leedcode的第二题：Youaregiventwolinkedlistsrepresentingtwonon-negativenumbers.Thedigitsarestoredinreverseorderandeachoftheirnodescontainasingledigit.Addthetwonumbersandreturnitasalinkedl

1、twosum——这是leedcode的第一题：Givenanarrayofintegers,returnindicesofthetwonumberssuchthattheyadduptoaspecifictarget.Youmayassumethateachinputwouldhaveexactlyonesolution.Example

Mergetwosortedlinkedlistsandreturnitasanewlist.Thenewlistshouldbemadebysplicingtogetherthenodesofthefirsttwolists.packageleedcode

packageleedcode; importjava.lang.reflect.Array; importjava.util.ArrayList; importjavax.crypto.spec.IvParameterSpec

leedcode79.WordSearchGivena2Dboardandaword,findifthewordexistsinthegrid.Thewordcanbeconstructedfromlettersofsequentiallyadjacentcell

RelatedtoquestionExcelSheetColumnTitleGivenacolumntitleasappearinanExcelsheet,returnitscorrespondingcolumnnumber.解题思路：进制的转换，26进制转10进制，注意点就是A-Z不是以0开头，所以要记得加1。java版：publicclassSolution{publicinttitleToN

RelatedtoquestionExcelSheetColumnTitleGivenacolumntitleasappearinanExcelsheet,returnitscorrespondingcolumnnumber.解题思路：进制的转换，26进制转10进制，注意点就是A-Z不是以0开头，所以要记得加1。java版：publicclassSolution{ publicinttitleTo

packageleedcode; publicclasstest{ inthisage;//定义一个全局变量 //构造函数,必须和类名字一致 publictest(Stringname){ //这个构造器仅有一个参数

Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations: get and set. get(key) - Get the value (will always be positi

Given a binary tree, return the postorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3   return [3,2,1]. /

点击打开题目链接 今天只是写了递归的版本，因为还没想好怎么用迭代来实现，可以写的过程中，有一点是有疑问的，虽然我的代码可以AC。 问题是：主调函数是可以使用子函数中返回的在子函数中定义的vector. 我认为在被调函数执行结束之后，其分配的空间是应该被释放的，所以在被调函数中定义的变量也是不可以被主调函数中使用的...可能是C++的基础知识又给忘了，有空要拾起来了。 附上代码（递归版）

点击打开题目链接 题目意思就是自己实现一个atoi函数，也就是将字符串转换成int型。 关于INT_MAX和INT_MIN， 只是在<limits.h>文件中定义的宏..分别是int型可以表示的最大值和最小值 还有就是定义大整数常量的时候，会出现这种警告：warning: this decimal constant is unsigned only in ISO C90 c的标

题目链接 题意： find the maximum positive difference between the price on the ith day and the jth day  附上代码： 1 class Solution { 2 public: 3 int maxProfit(vector<int> &prices) { 4

Follow up for N-Queens problem. Now, instead outputting board configurations, return the total number of distinct solutions. public class Solution { //本题类似于N-Queens，这个更简单一些，只需要求出解法的个数即可，因此没有

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 so

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?   In order to fulfill the follow

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 fil

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 should run in 

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,

Find Minimum in Rotated Sorted Array   Total Accepted: 44929 Total Submissions: 135513 My Submissions Question  Solution    Suppose a sorted array is rotated

Given a linked list, return the node where the cycle begins. If there is no cycle, return null. Follow up:Can you solve it without using extra space? 因为fast的速度是slow的两倍，所以fast走的距离是slow的两倍，有 2(

Given a linked list and a value x, partition it such that all nodes less than x come before nodes greater than or equal to x. You should preserve the original relative order of th

Given n non-negative integers representing the histogram's bar height where the width of each bar is 1, find the area of largest rectangle in the histogram. Above is a histogram where wid

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 tr

Given an array of integers and an integer k, find out whether there there are two distinct indices i and j in the array such that nums[i] = nums[j] and the differenc

/** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int x) { val = x; } * } */ public class Solution { public ListNo

Description: Count the number of prime numbers less than a non-negative number, n public class Solution { public int countPrimes(int n) { if(n<3) return 0; int res=0;

Given an array of strings, return all groups of strings that are anagrams. Note: All inputs will be in lower-case. public class Solution { public List<String> anagrams(String[] strs) {

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. Determine if yo

public class Solution { public double myPow(double x, int n) { //利用二分法，通过递归加速计算 //注意：1.判断n是否为负 // 2.递归结束条件，n==1和n==0 // 3.n的奇偶不同处理方式 if(n<

Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example,[1,1,2] have the following unique permutations:[1,1,2], [1,2,1], and [

Straight forward idea. Just like the way we multiply numbers. Don't forget considering the carry and be careful. e.g.  123*456,what we usually do is:      123*    456----

Given a collection of numbers, return all possible permutations. For example,[1,2,3] have the following permutations:[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,

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. Your goal is to

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 use

The count-and-say sequence is the sequence of integers beginning as follows:1, 11, 21, 1211, 111221, ... 1 is read off as "one 1" or 11.11 is read off as "

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.

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

Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring. For "(()", the longest valid parenth

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 is not

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 ar

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 

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 o

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 in pl