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public int reverseBits(int n) { int r = 0; for(int i = 0;i < 32 && n != 0;i++){ r= r<<1; r = r|(n&1); n = n>>1; } return r; }public int hammingWeight(int n) { int r = 0...

Reverse Nodes in k-Group Given a linked list, reverse the nodes of a linked listk at a time and return its modified list.k is a positive integer and is less than or equal to the length of the li

Remove Duplicates from Sorted ArrayGiven a sorted array, remove the duplicates in place such that each element appear onlyonce and return the new length.Do not allocate extra space for another

Remove ElementGiven an array and a value, 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 in place with cons

Implement strStrImplement strStr().Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.对haystack进行遍历，比较当前下标下，长度为needle.length()长的字符串是否与

Divide Two Integers Divide two integers without using multiplication, division and mod operator.If it is overflow, return MAX_INT.package leetcode;public class leet29 { public static

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

Substring with Concatenation of All Words转载：www.cnblogs.com/zihaowang/p/4507979.htmlYou are given a string, s, and a list of words,words, that are all of the same length. Find all starti

Next Permutation参考：https://yq.aliyun.com/articles/863Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.If such arrangement i

Merge k Sorted Lists  参考：http://www.cnblogs.com/TenosDoIt/p/3673188.htmlMerge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.解一：因为前面有一道题是两条

Generate ParenthesesGiven n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.For example, given n = 3, a solution set is:[ "((()))", "(()(

leetcode14:Longest Common Prefix Write a function to find the longest common prefix string amongst an array of strings.循环的判断数组中每一个字符串在相同的下标是否有相同的值（当然还要加入相应的判断匹配终止的条件），这样遍可以找出最长的公共前缀package lee

18. 4SumGiven an array S of n integers, are there elementsa, 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:

3Sum Closest Given an array S of n integers, find three integers inS such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input wo

Letter Combinations of a Phone NumberGiven a digit string, return all possible letter combinations that the number could represent.A mapping of digit to letters (just like on the telephone butto

Remove Nth Node From End of ListGiven a linked list, remove the nth node from the end of list and return its head.For example, Given linked list: 1->2->3->4->5, and n = 2. After removing

Valid ParenthesesGiven a string containing just the characters '(', ')', '{', '}', '[' and']', determine if the input string is valid.The brackets must close in the correct order, "()" and "

Merge Two Sorted ListsMerge 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.两个单链表的合并package leetcode;

Swap Nodes in Pairs Given a linked list, swap every two adjacent nodes and return its head.For example,Given 1->2->3->4, you should return the list as 2->1->4->3.Your algorithm should use on

3Sum我觉得做算法题，一般在不能一下子给出最终的解得时候，应该循序渐进的结局问题，先给出一个近似正确的答案，并进行不断地修正，一步一步的逼近最终得答案，就向这道题一样，可以先实现有重复解得程序，再在这个程序的基础上实现无重复的解。package leetcode;import java.util.ArrayList;import java.util.Iterator;impo