leetCode笔记

LeetCode笔记：371. Sum of Two Integers

问题：Calculatethesumoftwointegersaandb,butyouarenotallowedtousetheoperator+and-.Example:Givena=1andb=2,return3.大意：计算a和b两个整数的和，但是不能用+或-运算符。比如：给出a=1和b=2，返回3.思路：这道题乍看之下很简单，计算两个数之和嘛，但问题在于不能直接使用加号和减号，这就尴尬了，不
Cloudox_·2016-09-06 11:13

LeetCode笔记：371. Sum of Two Integers

问题：Calculatethesumoftwointegersaandb,butyouarenotallowedtousetheoperator+and-.Example:Givena=1andb=2,return3.大意：计算a和b两个整数的和，但是不能用+或-运算符。比如：给出a=1和b=2，返回3.思路：这道题乍看之下很简单，计算两个数之和嘛，但问题在于不能直接使用加号和减号，这就尴尬了，不
Cloudox_·2016-09-06 11:00

Leetcode笔记(python)

326.PowerofThreeGivenaninteger,writeafunctiontodetermineifitisapowerofthree.（判断一个数是否是3的次方数，不使用循环和迭代）由于输入是int，正数范围是0-231，在此范围中允许的最大的3的次方数为319=1162261467，那么我们只要看这个数能否被n整除即可。classSolution(object):defisPo
跑者小越·2016-06-12 22:07

leetcode笔记—Reorder List

给一个链表 L: L0→L1→…→Ln-1→Ln,需要返回: L0→Ln→L1→Ln-1→L2→Ln-2→…思路1：voidreorderList(ListNode*head){ ListNode*p=head; while(p&&p->next) { ListNode*pnext=p->next;//记下下一个节点 ListNode*temp=p; if(p->next->next==NULL)
sinat_27935693·2016-05-11 10:00

leetcode笔记：Dungeon Game

一.题目描述Thedemonshadcapturedtheprincess(P)andimprisonedherinthebottom-rightcornerofadungeon.ThedungeonconsistsofMxNroomslaidoutina2Dgrid.Ourvaliantknight(K)wasinitiallypositionedinthetop-leftroomandmust
Herbert_Zero·2016-05-05 17:00

leetcode笔记：Dungeon Game

一.题目描述Thedemonshadcapturedtheprincess(P)andimprisonedherinthebottom-rightcornerofadungeon.ThedungeonconsistsofMxNroomslaidoutina2Dgrid.Ourvaliantknight(K)wasinitiallypositionedinthetop-leftroomandmust
liyuefeilong·2016-05-05 17:00

leetcode笔记：Excel Sheet Column Number

一.题目描述GivenacolumntitleasappearinanExcelsheet,returnitscorrespondingcolumnnumber.Forexample:A->1 B->2 C->3 ... Z->26 AA->27 AB->28二.题目分析该题的题意是，给定一个出现在Excel表格中的列标题，返回其对应的列号。其实就是编写一个函数实现字符串到整数的转换。观察测试用例
liyuefeilong·2016-05-05 16:00

leetcode笔记—翻转链表

1、翻转链表voidreverseNodes(ListNode*start,ListNode*end){//翻转链表 ListNode*second=start->next; ListNode*first=start; ListNode*temp; while(second!=end){ temp=second->next; second->next=first; first=second;
sinat_27935693·2016-05-05 09:00

leetcode笔记：Excel Sheet Column Number

一.题目描述GivenacolumntitleasappearinanExcelsheet,returnitscorrespondingcolumnnumber.Forexample:A->1 B->2 C->3 ... Z->26 AA->27 AB->28二.题目分析该题的题意是，给定一个出现在Excel表格中的列标题，返回其对应的列号。其实就是编写一个函数实现字符串到整数的转换。观察测试用例
Herbert_Zero·2016-05-05 00:00

LeetCode笔记：344. Reverse String

问题：Writeafunctionthattakesastringasinputandreturnsthestringreversed.Example:Givens=“hello”,return“olleh”.大意：写一个函数获取输入的字符串然后返回反转后后的字符串。比如：给出s=“hello”，返回”olleh”思路：思路很直接就想到，先把字符串拆分成一个个字符组成的数组，新建一个空字符串，然后
Cloudox_·2016-05-02 21:00

leetcode笔记—Find the Duplicate Number

Givenanarray nums containing n +1integerswhereeachintegerisbetween1and n (inclusive),provethatatleastoneduplicatenumbermustexist.Assumethatthereisonlyoneduplicatenumber,findtheduplicateone.Note:You mu
sinat_27935693·2016-05-02 19:00

leetcode笔记：Reverse Vowels of a String

一.题目描述Writeafunctionthattakesastringasinputandreverseonlythevowelsofastring.Example1:Givens="hello",return"holle".Example2:Givens="leetcode",return"leotcede".二.题目分析题目大意是，编写函数输入一个字符串，将其中的元音字母反转，其他字母位置不
liyuefeilong·2016-05-02 02:00

leetcode笔记：Reverse String

一.题目描述Writeafunctionthattakesastringasinputandreturnsthestringreversed.Example:Givens="hello",return"olleh".二.题目分析题目大意是，编写一个函数，输入为一字符串，返回反序的字符串。如输入s=“hello”，返回”olleh”。这是一道水题，但是可以用很多种方法去解决，对于开阔思路很有帮助，也
liyuefeilong·2016-05-02 01:00

LeetCode笔记：206. Reverse Linked List

题目：Reverseasinglylinkedlist.大意：反转一个简单链表。思路：题目的意思就是给出一个链表，本来是从头指向尾的，现在要你做成从尾指向头，并且返回原来的尾，现在的头。这个肯定是要用递归或者迭代来做。只要屡清楚过程，会比较绕。大体的流程就是，把下一个节点的next指向自己，一个个迭代、递归下去，最后返回最后的原来的尾节点他山之石：这里给出Discuss中最火的方法。迭代实现：pu
Cloudox_·2016-04-28 15:00

leetcode笔记—二进制数中1的个数

基本思想：x=x&(x-1)可以消除x最右边的1；1.给出一个32位的二进制数，统计其中1的个数classSolution{ public: inthammingWeight(uint32_tn){//n=n&(n-1)可以消去最右边的1 intres=0; while(n) { n=n&(n-1); res++; } returnres; } };2.翻转一个32位数classSolution{
sinat_27935693·2016-04-26 21:00

leetcode笔记：Merge Two Sorted Lists

一.题目描述Mergetwosortedlinkedlistsandreturnitasanewlist.Thenewlistshouldbemadebysplicingtogetherthenodesofthefirsttwolists.二.题目分析合并两个有序链表，递归或迭代均可以解决。三.示例代码/** *Definitionforsingly-linkedlist. *structList
liyuefeilong·2016-04-21 15:00

leetcode笔记：Maximal Square

一.题目描述Givena2Dbinarymatrixfilledwith0’sand1’s,findthelargestsquarecontainingall1’sandreturnitsarea.Forexample,giventhefollowingmatrix:10100 10111 11111 10010Return4.二.题目分析题目大意是，给定一个二维矩阵（只包含字符'0'和'1'），
liyuefeilong·2016-04-20 23:00

leetcode笔记：Remove Duplicate Letters

一.题目描述Givenastringwhichcontainsonlylowercaseletters,removeduplicateletterssothateveryletterappearonceandonlyonce.Youmustmakesureyourresultisthesmallestinlexicographicalorderamongallpossibleresults.Exa
liyuefeilong·2016-04-20 17:00

leetcode笔记—判断查找二叉树

首先说明一下二叉树和二叉搜索树的区别。二叉树指这样的树结构，它的每个结点的孩子数目最多为2个；二叉搜索树是一种二叉树，但是它有附加的一些约束条件，这些约束条件必须对每个结点都成立：结点node的左子树所有结点的值都小于node的值。结点node的右子树所有结点的值都大于node的值。结点node的左右子树同样都必须是二叉搜索树。假定当前结点值为k。对于二叉树中每个结点，判断其左孩子的值是否小于k，
sinat_27935693·2016-04-20 09:00

leetcode笔记：Integer Break

一.题目描述Givenapositiveintegern,breakitintothesumofatleasttwopositiveintegersandmaximizetheproductofthoseintegers.Returnthemaximumproductyoucanget.Forexample,givenn=2,return1(2=1+1);givenn=10,return36(10
liyuefeilong·2016-04-19 19:00

leetcode笔记：Remove Linked List Elements

一.题目描述Removeallelementsfromalinkedlistofintegersthathavevalueval.ExampleGiven:1-->2-->6-->3-->4-->5-->6,val=6Return:1-->2-->3-->4-->5Credits:Specialthanksto@mithmattforaddingthisproblemandcreatingallt
liyuefeilong·2016-04-19 01:00

leetcode笔记：Implement Trie (Prefix Tree)

一.题目描述Implementatriewithinsert,search,andstartsWithmethods.Note:Youmayassumethatallinputsareconsistoflowercaselettersa-z.二.题目分析题目大意很简单，就是实现字典树，其中包括插入、查找和前缀查找三个方法。可以假设所有的输入只包含小写字母a-z。本题考查字典树数据结构的基础知识。需
liyuefeilong·2016-04-18 23:00

leetcode笔记：Power of Four

一.题目描述Givenaninteger(signed32bits),writeafunctiontocheckwhetheritisapowerof4.Example:Givennum=16,returntrue.Givennum=5,returnfalse.Followup:Couldyousolveitwithoutloops/recursion?二.题目分析题目的大意是，给定一个32位有符
liyuefeilong·2016-04-18 19:00

LeetCode笔记：169. Majority Element

题目：Givenanarrayofsizen,findthemajorityelement.Themajorityelementistheelementthatappearsmorethan⌊n/2⌋times.Youmayassumethatthearrayisnon-emptyandthemajorityelementalwaysexistinthearray.大意：给出一个尺寸为n的数组，找
Cloudox_·2016-04-16 15:00

LeetCode笔记：169. Majority Element

题目：Givenanarrayofsizen,findthemajorityelement.Themajorityelementistheelementthatappearsmorethan⌊n/2⌋times.Youmayassumethatthearrayisnon-emptyandthemajorityelementalwaysexistinthearray.大意：给出一个尺寸为n的数组，找
Cloudox_·2016-04-16 15:00

LeetCode笔记：217. Contains Duplicate

题目：Givenanarrayofintegers,findifthearraycontainsanyduplicates.Yourfunctionshouldreturntrueifanyvalueappearsatleasttwiceinthearray,anditshouldreturnfalseifeveryelementisdistinct.大意：给出一个int型的数组，判断数组是否包含
Cloudox_·2016-04-15 10:00

LeetCode笔记：217. Contains Duplicate

题目：Givenanarrayofintegers,findifthearraycontainsanyduplicates.Yourfunctionshouldreturntrueifanyvalueappearsatleasttwiceinthearray,anditshouldreturnfalseifeveryelementisdistinct.大意：给出一个int型的数组，判断数组是否包含
Cloudox_·2016-04-15 10:00

LeetCode笔记：171. Excel Sheet Column Number

题目：RelatedtoquestionExcelSheetColumnTitleGivenacolumntitleasappearinanExcelsheet,returnitscorrespondingcolumnnumber.Forexample:A->1B->2C->3…Z->26AA->27AB->28大意：与题目ExcelSheetColumnTitle相关给一个像Excel中显示的列
Cloudox_·2016-04-13 20:00

LeetCode笔记：171. Excel Sheet Column Number

题目：RelatedtoquestionExcelSheetColumnTitleGivenacolumntitleasappearinanExcelsheet,returnitscorrespondingcolumnnumber.Forexample:A->1B->2C->3…Z->26AA->27AB->28大意：与题目ExcelSheetColumnTitle相关给一个像Excel中显示的列
Cloudox_·2016-04-13 20:00

leetcode笔记-Path Sum

关于路径问题：1.输出所有的路径voidfindPath(vector>&ret,vectortmp,TreeNode*root) { if(root==NULL)return; tmp.push_back(root->val); if(root->left==NULL&&root->right==NULL) { ret.push_back(tmp); return; } if(root->lef
sinat_27935693·2016-04-12 20:00

Leetcode笔记—最大路径和

public: intmaxPathSum(TreeNode*root){ intmaxsum=INT_MIN; dfs(root,maxsum); returnmaxsum; } intdfs(TreeNode*root,int&maxsum) { if(root==NULL)return0; intl=max(0,dfs(root->left,maxsum)); intr=max(0,dfs(
sinat_27935693·2016-04-12 17:00

leetcode笔记：Reconstruct Itinerary

一.题目描述Givenalistofairlineticketsrepresentedbypairsofdepartureandarrivalairports[from,to],reconstructtheitineraryinorder.AlloftheticketsbelongtoamanwhodepartsfromJFK.Thus,theitinerarymustbeginwithJFK.N
liyuefeilong·2016-04-11 22:00

leetcode笔记-Kth Smallest Element in a BST

思路：定义一个中序遍历的函数，调用中序遍历将各个节点都存在VECTOR中，其中的数是从小到大的排列的，再取第K个最小的值/** *Definitionforabinarytreenode. *structTreeNode{ *intval; *TreeNode*left; *TreeNode*right; *TreeNode(intx):val(x),left(NULL),right(NULL){
sinat_27935693·2016-04-11 18:00

leetcode笔记-层序遍历

/** *Definitionforabinarytreenode. *structTreeNode{ *intval; *TreeNode*left; *TreeNode*right; *TreeNode(intx):val(x),left(NULL),right(NULL){} *} */ classSolution{ public: vector>levelOrder(TreeNode*ro
sinat_27935693·2016-04-10 19:00

leetcode笔记-zigzag层序遍历

zigzag层序遍历 /** *Definitionforabinarytreenode. *structTreeNode{ *intval; *TreeNode*left; *TreeNode*right; *TreeNode(intx):val(x),left(NULL),right(NULL){} *}; */ classSolution{ public: vector>zigzagLeve
sinat_27935693·2016-04-10 16:00

leetcode笔记：Invert Binary Tree

一.题目描述Invertabinarytree.4 /\27 /\/\1369to4 /\72 /\/\9631Trivia:ThisproblemwasinspiredbythisoriginaltweetbyMaxHowell:Google:90%ofourengineersusethesoftwareyouwrote(Homebrew),butyoucan’tinvertabinarytre
liyuefeilong·2016-04-07 16:00

leetcode笔记：Counting Bits

一.题目描述Givenanonnegativeintegernumbernum.Foreverynumbersiintherange0≤i≤numcalculatethenumberof1’sintheirbinaryrepresentationandreturnthemasanarray.Example:Fornum=5youshouldreturn[0,1,1,2,1,2].Followup:
liyuefeilong·2016-04-07 15:00

数据结构与算法之leetcode刷题笔记

leetcode笔记1、PowerofThreeJava版：https://leetcode.com/submissions/detail/51726417/2、RisingTemperatureJava
chongshangyunxiao321·2016-04-06 17:42

数据结构与算法之leetcode刷题笔记

leetcode笔记1、PowerofThree    Java版：https://leetcode.com/submissions/detail/51726417/ 2、RisingTemperatureJava
chongshangyunxiao321·2016-04-06 17:00

LeetCode笔记：242. Valid Anagram

题目：Giventwostringssandt,writeafunctiontodetermineiftisananagramofs.Forexample,s=“anagram”,t=“nagaram”,returntrue.s=“rat”,t=“car”,returnfalse.Note:Youmayassumethestringcontainsonlylowercasealphabets.Fo
Cloudox_·2016-04-04 21:00

LeetCode笔记：100. Same Tree

题目：Giventwobinarytrees,writeafunctiontocheckiftheyareequalornot.Twobinarytreesareconsideredequaliftheyarestructurallyidenticalandthenodeshavethesamevalue.大意：给出两个二叉树，写一个函数来检查两者是否相等。所谓相等，是指他们结构相同且节点有同样的
Cloudox_·2016-03-29 14:00

LeetCode笔记：100. Same Tree

题目：Giventwobinarytrees,writeafunctiontocheckiftheyareequalornot.Twobinarytreesareconsideredequaliftheyarestructurallyidenticalandthenodeshavethesamevalue.大意：给出两个二叉树，写一个函数来检查两者是否相等。所谓相等，是指他们结构相同且节点有同样的
Cloudox_·2016-03-29 14:00

LeetCode笔记：237. Delete Node in a Linked List

题目：Writeafunctiontodeleteanode(exceptthetail)inasinglylinkedlist,givenonlyaccesstothatnode.Supposedthelinkedlistis1->2->3->4andyouaregiventhethirdnodewithvalue3,thelinkedlistshouldbecome1->2->4afterca
Cloudox_·2016-03-28 19:00

LeetCode笔记：237. Delete Node in a Linked List

题目：Writeafunctiontodeleteanode(exceptthetail)inasinglylinkedlist,givenonlyaccesstothatnode.Supposedthelinkedlistis1->2->3->4andyouaregiventhethirdnodewithvalue3,thelinkedlistshouldbecome1->2->4afterca
Cloudox_·2016-03-28 19:00

leetcode笔记：Number of 1 Bits

一.题目描述Writeafunctionthattakesanunsignedintegerandreturnsthenumberof'1'bitsithas(alsoknownastheHammingweight).Forexample,the32-bitinteger'11'hasbinaryrepresentation00000000000000000000000000001011,soth
liyuefeilong·2016-03-28 18:00

LeetCode笔记：283. Move Zeroes

题目：Givenanarraynums,writeafunctiontomoveall0’stotheendofitwhilemaintainingtherelativeorderofthenon-zeroelements.Forexample,givennums=[0,1,0,3,12],aftercallingyourfunction,numsshouldbe[1,3,12,0,0].Note
Cloudox_·2016-03-28 15:00

LeetCode笔记：283. Move Zeroes

题目：Givenanarraynums,writeafunctiontomoveall0’stotheendofitwhilemaintainingtherelativeorderofthenon-zeroelements.Forexample,givennums=[0,1,0,3,12],aftercallingyourfunction,numsshouldbe[1,3,12,0,0].Note
Cloudox_·2016-03-28 15:00

LeetCode笔记：226. Invert Binary Tree

问题：Invertabinarytree.toTrivia:Google:90%ofourengineersusethesoftwareyouwrote(Homebrew),>butyoucan’tinvertabinarytreeonawhiteboardsofuckoff.大意：反转一个二叉树。从到琐事：Google表示如果你连反转二叉树都做不到就滚吧。思路：对于二叉树的每个子节点的左右节点都
Cloudox_·2016-03-26 15:00

LeetCode笔记：226. Invert Binary Tree

问题：Invertabinarytree.toTrivia:Google:90%ofourengineersusethesoftwareyouwrote(Homebrew),>butyoucan’tinvertabinarytreeonawhiteboardsofuckoff.大意：反转一个二叉树。从到琐事：Google表示如果你连反转二叉树都做不到就滚吧。思路：对于二叉树的每个子节点的左右节点都
Cloudox_·2016-03-26 15:00

LeetCode笔记：104.Maximum Depth of Binary Tree

问题：Givenabinarytree,finditsmaximumdepth.Themaximumdepthisthenumberofnodesalongthelongestpathfromtherootnodedowntothefarthestleafnode.大意：给出一个二叉树，找到其最大的深度。最大深度是指从根节点到最远的叶子节点的最长距离的节点数。思路：要探索二叉树的深度，用递归比较方
Cloudox_·2016-03-26 14:00
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