leetCode笔记第7页

103. leetcode笔记(1~60)

d1leet1:两数之和https://leetcode-cn.com/problems/two-sum给定nums=[2,7,11,15],target=9因为nums[0]+nums[1]=2+7=9所以返回[0,1]【hashmap存储】classSolution:deftwoSum(self,nums:List[int],target:int)->List[int]:#边界值判断ifnot

十里江城·2020-05-11 22:34

LeetCode笔记（数组双指针，同时遍历左右子树，最大子序和）

121.买卖股票的最佳时机*-easy还是太菜，想了很久用双指针来记录最小值和最大利润，每进来一个数就要比较是否为最小数，并且比较此时卖出是否比之前卖出赚的更多//14.57//15.25classSolution{public:intmaxProfit(vector&prices){if(prices.size()sum){sum=prices[i]-small;}if(small>prices

feitianguaishou·2020-04-26 14:15

LeetCode笔记：435. Non-overlapping Intervals

问题：Givenacollectionofintervals,findtheminimumnumberofintervalsyouneedtoremovetomaketherestoftheintervalsnon-overlapping.Note:1、Youmayassumetheinterval'sendpointisalwaysbiggerthanitsstartpoint.2、Interv

Cloudox_·2020-04-13 13:10

LeetCode笔记：728. Self Dividing Numbers

问题（Easy）：Aself-dividingnumberisanumberthatisdivisiblebyeverydigititcontains.Forexample,128isaself-dividingnumberbecause128%1==0,128%2==0,and128%8==0.Also,aself-dividingnumberisnotallowedtocontainthedi

Cloudox_·2020-04-13 04:39

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_·2020-04-12 00:17

LeetCode笔记：463. Island Perimeter

问题（Easy）：Youaregivenamapinformofatwo-dimensionalintegergridwhere1representslandand0representswater.Gridcellsareconnectedhorizontally/vertically(notdiagonally).Thegridiscompletelysurroundedbywater,andt

Cloudox_·2020-04-11 19:26

LeetCode笔记：598. Range Addition II

问题（Easy）：Givenanm*nmatrixMinitializedwithall0'sandseveralupdateoperations.Operationsarerepresentedbya2Darray,andeachoperationisrepresentedbyanarraywithtwopositiveintegersaandb,whichmeansM[i][j]shouldb

Cloudox_·2020-04-10 23:57

LeetCode笔记：482. License Key Formatting

问题：NowyouaregivenastringS,whichrepresentsasoftwarelicensekeywhichwewouldliketoformat.ThestringSiscomposedofalphanumericalcharactersanddashes.Thedashessplitthealphanumericalcharacterswithinthestringint

Cloudox_·2020-04-02 19:39

LeetCode笔记：144. Binary Tree Preorder Traversal

问题：Givenabinarytree,returnthepreordertraversalofitsnodes'values.Forexample:Givenbinarytree{1,#,2,3},image.pngreturn[1,2,3].Note:Recursivesolutionistrivial,couldyoudoititeratively?大意：给出一个二叉树，返回节点值的前序遍历

Cloudox_·2020-04-02 08:48

LeetCode笔记：500. Keyboard Row

问题（Easy）：GivenaListofwords,returnthewordsthatcanbetypedusinglettersofalphabetononlyonerow'sofAmericankeyboardliketheimagebelow.Example1:Input:["Hello","Alaska","Dad","Peace"]Output:["Alaska","Dad"]Not

Cloudox_·2020-04-01 15:07

LeetCode笔记：496. Next Greater Element I

问题（Easy）：Youaregiventwoarrays(withoutduplicates)nums1andnums2wherenums1’selementsaresubsetofnums2.Findallthenextgreaternumbersfornums1'selementsinthecorrespondingplacesofnums2.TheNextGreaterNumberofan

Cloudox_·2020-04-01 15:35

LeetCode笔记：485. Max Consecutive Ones

问题（Easy）：Givenabinaryarray,findthemaximumnumberofconsecutive1sinthisarray.Example1:Input:[1,1,0,1,1,1]Output:3Explanation:Thefirsttwodigitsorthelastthreedigitsareconsecutive1s.Themaximumnumberofconsec

Cloudox_·2020-03-30 22:39

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_·2020-03-30 10:32

LeetCode笔记--动态规划

慕北人·2020-03-30 01:18

LeetCode笔记：232. Implement Queue using Stacks

问题：Implementthefollowingoperationsofaqueueusingstacks.push(x)--Pushelementxtothebackofqueue.pop()--Removestheelementfrominfrontofqueue.peek()--Getthefrontelement.empty()--Returnwhetherthequeueisempty.

Cloudox_·2020-03-28 03:44

LeetCode笔记：121. Best Time to Buy and Sell Stock

问题：Sayyouhaveanarrayforwhichtheithelementisthepriceofagivenstockondayi.Ifyouwereonlypermittedtocompleteatmostonetransaction(ie,buyoneandselloneshareofthestock),designanalgorithmtofindthemaximumprofit.

Cloudox_·2020-03-28 01:45

LeetCode笔记：19. Remove Nth Node From End of List

问题：Givenalinkedlist,removethenthnodefromtheendoflistandreturnitshead.Forexample,Givenlinkedlist:1->2->3->4->5,andn=2.Afterremovingthesecondnodefromtheend,thelinkedlistbecomes1->2->3->5.Note:Givennwill

Cloudox_·2020-03-26 22:02

LeetCode笔记：202. Happy Number

问题：Writeanalgorithmtodetermineifanumberis"happy".Ahappynumberisanumberdefinedbythefollowingprocess:Startingwithanypositiveinteger,replacethenumberbythesumofthesquaresofitsdigits,andrepeattheprocessunt

Cloudox_·2020-03-26 12:46

LeetCode笔记：617. Merge Two Binary Trees

问题（Easy）:Giventwobinarytreesandimaginethatwhenyouputoneofthemtocovertheother,somenodesofthetwotreesareoverlappedwhiletheothersarenot.Youneedtomergethemintoanewbinarytree.Themergeruleisthatiftwonodesov

Cloudox_·2020-03-26 04:07

LeetCode笔记：526. Beautiful Arrangement

问题：SupposeyouhaveNintegersfrom1toN.WedefineabeautifularrangementasanarraythatisconstructedbytheseNnumberssuccessfullyifoneofthefollowingistruefortheithposition(1≤i≤N)inthisarray:Thenumberattheithposit

Cloudox_·2020-03-25 13:51

LeetCode笔记：223. Rectangle Area

问题：Findthetotalareacoveredbytworectilinearrectanglesina2Dplane.Eachrectangleisdefinedbyitsbottomleftcornerandtoprightcornerasshowninthefigure.image.pngAssumethatthetotalareaisneverbeyondthemaximumposs

Cloudox_·2020-03-25 05:46

LeetCode笔记：263. Ugly Number

问题：Writeaprogramtocheckwhetheragivennumberisanuglynumber.Uglynumbersarepositivenumberswhoseprimefactorsonlyinclude2,3,5.Forexample,6,8areuglywhile14isnotuglysinceitincludesanotherprimefactor7.Notethat

Cloudox_·2020-03-24 23:37

LeetCode笔记：237. Delete Node in a Linked List

题目：Writeafunctiontodeleteanode(exceptthetail)inasinglylinkedlist,givenonlyaccesstothatnode.Supposedthelinkedlistis1->2->3->4andyouaregiventhethirdnodewithvalue3,thelinkedlistshouldbecome1->2->4afterca

Cloudox_·2020-03-23 00:45

LeetCode笔记：225. Implement Stack using Queues

问题：Implementthefollowingoperationsofastackusingqueues.push(x)--Pushelementxontostack.pop()--Removestheelementontopofthestack.top()--Getthetopelement.empty()--Returnwhetherthestackisempty.Notes:Youmust

Cloudox_·2020-03-22 18:42

LeetCode笔记：383. Ransom Note

问题：Givenanarbitraryransomnotestringandanotherstringcontaininglettersfromallthemagazines,writeafunctionthatwillreturntrueiftheransomnotecanbeconstructedfromthemagazines;otherwise,itwillreturnfalse.Each

Cloudox_·2020-03-22 09:20

LeetCode笔记：343. Integer Break

问题：Givenapositiveintegern,breakitintothesumofatleasttwopositiveintegersandmaximizetheproductofthoseintegers.Returnthemaximumproductyoucanget.Forexample,givenn=2,return1(2=1+1);givenn=10,return36(10=3+

Cloudox_·2020-03-22 07:34

LeetCode笔记：292.Nim Game

问题：YouareplayingthefollowingNimGamewithyourfriend:Thereisaheapofstonesonthetable,eachtimeoneofyoutaketurnstoremove1to3stones.Theonewhoremovesthelaststonewillbethewinner.Youwilltakethefirstturntoremove

Cloudox_·2020-03-20 08:03

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_·2020-03-18 11:13

LeetCode笔记：400. Nth Digit

问题：Findthenthdigitoftheinfiniteintegersequence1,2,3,4,5,6,7,8,9,10,11,...Note:nispositiveandwillfitwithintherangeofa32-bitsignedinteger(nreduce+num*i){lastNum=lastNum+num;reduce=reduce+num*i;num=num*1

Cloudox_·2020-03-17 23:20

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_·2020-03-17 22:42

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_·2020-03-14 18:31

LeetCode笔记：406. Queue Reconstruction by Height

问题：Supposeyouhavearandomlistofpeoplestandinginaqueue.Eachpersonisdescribedbyapairofintegers(h,k),wherehistheheightofthepersonandkisthenumberofpeopleinfrontofthispersonwhohaveaheightgreaterthanorequalt

Cloudox_·2020-03-10 16:36

LeetCode笔记：118. Pascal's Triangle

问题：GivennumRows,generatethefirstnumRowsofPascal'striangle.Forexample,givennumRows=5,Return[[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]大意：给出一个行数，生出对应行数的杨辉三角形。比如，给出行数=5。返回[[1],[1,1],[1,2,1],[1,3,3,1],[1,4,

Cloudox_·2020-03-10 02:09

LeetCode笔记：67. Add Binary

问题：Giventwobinarystrings,returntheirsum(alsoabinarystring).Forexample,a="11"b="1"Return"100".大意：给出两个二进制字符串，返回它们的和（同样是二进制字符串）。例子：a="11"b="1"返回"100".思路：这其实就是一个模拟二进制加法的问题。如果某一位两个数都是0，结果的这一位也为0，有一个1就是1，如果

Cloudox_·2020-03-09 18:03

LeetCode笔记：378. Kth Smallest Element in a Sorted Matrix

问题：Givenanxnmatrixwhereeachoftherowsandcolumnsaresortedinascendingorder,findthekthsmallestelementinthematrix.Notethatitisthekthsmallestelementinthesortedorder,notthekthdistinctelement.Example:image.pn

Cloudox_·2020-03-09 07:59

LeetCode笔记：508. Most Frequent Subtree Sum

问题：Giventherootofatree,youareaskedtofindthemostfrequentsubtreesum.Thesubtreesumofanodeisdefinedasthesumofallthenodevaluesformedbythesubtreerootedatthatnode(includingthenodeitself).Sowhatisthemostfrequ

Cloudox_·2020-03-09 06:09

LeetCode笔记：498. Diagonal Traverse

问题：GivenamatrixofMxNelements(Mrows,Ncolumns),returnallelementsofthematrixindiagonalorderasshowninthebelowimage.Example:Input:[[1,2,3],[4,5,6],[7,8,9]]Output:[1,2,4,7,5,3,6,8,9]Explanation:image.pngNot

Cloudox_·2020-03-08 07:08

LeetCode笔记：386. Lexicographical Numbers

问题：Givenanintegern,return1-ninlexicographicalorder.Forexample,given13,return:[1,10,11,12,13,2,3,4,5,6,7,8,9].Pleaseoptimizeyouralgorithmtouselesstimeandspace.Theinputsizemaybeaslargeas5,000,000.思路：给出一

Cloudox_·2020-03-05 23:39

LeetCode笔记：89. Gray Code

问题：Thegraycodeisabinarynumeralsystemwheretwosuccessivevaluesdifferinonlyonebit.Givenanon-negativeintegernrepresentingthetotalnumberofbitsinthecode,printthesequenceofgraycode.Agraycodesequencemustbegin

Cloudox_·2020-03-04 14:52

LeetCode笔记：455. Assign Cookies

问题：Assumeyouareanawesomeparentandwanttogiveyourchildrensomecookies.But,youshouldgiveeachchildatmostonecookie.Eachchildihasagreedfactorgi,whichistheminimumsizeofacookiethatthechildwillbecontentwith;and

Cloudox_·2020-03-04 05:38

LeetCode笔记：409. Longest Palindrome

问题：Givenastringwhichconsistsoflowercaseoruppercaseletters,findthelengthofthelongestpalindromesthatcanbebuiltwiththoseletters.Thisiscasesensitive,forexample"Aa"isnotconsideredapalindromehere.Note:Assum

Cloudox_·2020-03-04 00:41

LeetCode笔记：319. Bulb Switcher

问题：Therearenbulbsthatareinitiallyoff.Youfirstturnonallthebulbs.Then,youturnoffeverysecondbulb.Onthethirdround,youtoggleeverythirdbulb(turningonifit'sofforturningoffifit'son).Fortheithround,youtoggleev

Cloudox_·2020-03-03 07:13

LeetCode笔记：413. Arithmetic Slices

问题：Asequenceofnumberiscalledarithmeticifitconsistsofatleastthreeelementsandifthedifferencebetweenanytwoconsecutiveelementsisthesame.Forexample,thesearearithmeticsequence:1,3,5,7,97,7,7,73,-1,-5,-9Thef

Cloudox_·2020-03-01 18:30

LeetCode笔记：160. Intersection of Two Linked Lists

问题：Writeaprogramtofindthenodeatwhichtheintersectionoftwosinglylinkedlistsbegins.Forexample,thefollowingtwolinkedlists:image.pngbegintointersectatnodec1.Notes:Ifthetwolinkedlistshavenointersectionatall

Cloudox_·2020-02-29 14:48

LeetCode笔记：258.Add Digits

问题：Givenanon-negativeintegernum,repeatedlyaddallitsdigitsuntiltheresulthasonlyonedigit.Forexample:Givennum=38,theprocessislike:3+8=11,1+1=2.Since2hasonlyonedigit,returnit.Followup:Couldyoudoitwithouta

Cloudox_·2020-02-27 15:47

LeetCode笔记：374. Guess Number Higher or Lower

问题：WeareplayingtheGuessGame.Thegameisasfollows:Ipickanumberfrom1ton.YouhavetoguesswhichnumberIpicked.Everytimeyouguesswrong,I'lltellyouwhetherthenumberishigherorlower.Youcallapre-definedAPIguess(intnu

Cloudox_·2020-02-26 13:31

LeetCode笔记：561. Array Partition I

问题（Easy）：Givenanarrayof2nintegers,yourtaskistogrouptheseintegersintonpairsofinteger,say(a1,b1),(a2,b2),...,(an,bn)whichmakessumofmin(ai,bi)forallifrom1tonaslargeaspossible.Example1:Input:[1,4,3,2]Outp

Cloudox_·2020-02-25 20:06

LeetCode笔记：637. Average of Levels in Binary Tree

问题（Easy）：Givenanon-emptybinarytree,returntheaveragevalueofthenodesoneachlevelintheformofanarray.Example1:Input:Output:[3,14.5,11]Explanation:Theaveragevalueofnodesonlevel0is3,onlevel1is14.5,andonlevel

Cloudox_·2020-02-24 07:24

LeetCode笔记：46. Permutations

问题：Givenacollectionofdistinctnumbers,returnallpossiblepermutations.Forexample,[1,2,3]havethefollowingpermutations:[[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]大意：给出一个不同数字的集合，返回所有可能的排列。比如：[1,2,3]有下

Cloudox_·2020-02-23 00:28

LeetCode笔记：557. Reverse Words in a String III

问题（Easy）：Givenastring,youneedtoreversetheorderofcharactersineachwordwithinasentencewhilestillpreservingwhitespaceandinitialwordorder.Example1:Input:"Let'stakeLeetCodecontest"Output:"s'teLekatedoCteeLt

Cloudox_·2020-02-22 04:09

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