leet 第13页

Leet Code OJ 110. Balanced Binary Tree [Difficulty: Easy]

题目：Givenabinarytree,determineifitisheight-balanced.Forthisproblem,aheight-balancedbinarytreeisdefinedasabinarytreeinwhichthedepthofthetwosubtreesofeverynodeneverdifferbymorethan1.翻译：给定一个二叉树，检测它是否是高度平衡

Lnho2015·2016-03-16 14:00

Leet Code OJ 1. Two Sum [Difficulty: Easy]

题目：Givenanarrayofintegers,returnindicesofthetwonumberssuchthattheyadduptoaspecifictarget.Youmayassumethateachinputwouldhaveexactlyonesolution.Example:Givennums=[2,7,11,15],target=9,Becausenums[0]+nums

Lnho2015·2016-03-14 20:00

Leet Code OJ 191. Number of 1 Bits [Difficulty: Easy]

题目：Writeafunctionthattakesanunsignedintegerandreturnsthenumberof’1’bitsithas(alsoknownastheHammingweight).Forexample,the32-bitinteger’11’hasbinaryrepresentation00000000000000000000000000001011,sothefu

Lnho2015·2016-03-14 15:00

Leet Code OJ 191. Number of 1 Bits [Difficulty: Easy]

题目：Writeafunctionthattakesanunsignedintegerandreturnsthenumberof’1’bitsithas(alsoknownastheHammingweight).Forexample,the32-bitinteger’11’hasbinaryrepresentation00000000000000000000000000001011,sothefu

Lnho2015·2016-03-14 15:00

Leet-code144. Binary Tree Preorder Traversal

这是一道将二叉树先序遍历，题目不难。首先采用深搜递归/** *Definitionforabinarytreenode. *publicclassTreeNode{ *intval; *TreeNodeleft; *TreeNoderight; *TreeNode(intx){val=x;} *} */ publicclassSolution{ publicstaticList

SnailRen·2016-03-13 16:00

Leet Code OJ 260. Single Number III [Difficulty: Medium]

题目：Givenanarrayofnumbersnums,inwhichexactlytwoelementsappearonlyonceandalltheotherelementsappearexactlytwice.Findthetwoelementsthatappearonlyonce.Forexample:Givennums=[1,2,1,3,2,5],return[3,5].Note:Th

Lnho2015·2016-03-09 17:00

Leet Code OJ 102. Binary Tree Level Order Traversal [Difficulty: Easy]

题目:Givenabinarytree,returnthelevelordertraversalofitsnodes’values.(ie,fromlefttoright,levelbylevel).Forexample:Givenbinarytree{3,9,20,#,#,15,7},returnitslevelordertraversalas:[[3],[9,20],[15,7]]翻译：给定一

Lnho2015·2016-03-08 13:00

leetcode 139. Word Break

determineifscanbesegmentedintoaspace-separatedsequenceofoneormoredictionarywords.Forexample,givens="leetcode",dict=["leet

u014568921·2016-03-08 13:00

Leet Code OJ 26. Remove Duplicates from Sorted Array [Difficulty: Easy]

题目：Givenasortedarray,removetheduplicatesinplacesuchthateachelementappearonlyonceandreturnthenewlength.Donotallocateextraspaceforanotherarray,youmustdothisinplacewithconstantmemory.Forexample,Giveninpu

Lnho2015·2016-03-08 13:00

Leet Code OJ 26. Remove Duplicates from Sorted Array [Difficulty: Easy]

题目：Givenasortedarray,removetheduplicatesinplacesuchthateachelementappearonlyonceandreturnthenewlength.Donotallocateextraspaceforanotherarray,youmustdothisinplacewithconstantmemory.Forexample,Giveninpu

Lnho2015·2016-03-08 13:00

Leet Code OJ 326. Power of Three [Difficulty: Easy]

题目：Givenaninteger,writeafunctiontodetermineifitisapowerofthree.Followup:Couldyoudoitwithoutusinganyloop/recursion?翻译：给定一个整数，写一个函数去判断它是否是3的幂。更进一步：你能不使用循环或者递归来完成吗？代码:publicclassSolution{ publicbooleanis

Lnho2015·2016-03-07 16:00

Leet Code OJ 219. Contains Duplicate II [Difficulty: Easy]

题目:Givenanarrayofintegersandanintegerk,findoutwhethertherearetwodistinctindicesiandjinthearraysuchthatnums[i]=nums[j]andthedifferencebetweeniandjisatmostk.翻译：给定一个整数数组和一个整数k，找出是否存在下标i，j使得nums[i]=nums[j

Lnho2015·2016-03-07 14:00

Leet Code OJ 235. Lowest Common Ancestor of a Binary Search Tree [Difficulty: Easy]

题目:Givenabinarysearchtree(BST),findthelowestcommonancestor(LCA)oftwogivennodesintheBST.AccordingtothedefinitionofLCAonWikipedia:“ThelowestcommonancestorisdefinedbetweentwonodesvandwasthelowestnodeinTt

Lnho2015·2016-03-07 13:00

Leet Code OJ 235. Lowest Common Ancestor of a Binary Search Tree [Difficulty: Easy]

题目:Givenabinarysearchtree(BST),findthelowestcommonancestor(LCA)oftwogivennodesintheBST.AccordingtothedefinitionofLCAonWikipedia:“ThelowestcommonancestorisdefinedbetweentwonodesvandwasthelowestnodeinTt

Lnho2015·2016-03-07 13:00

Leet Code OJ 223. Rectangle Area [Difficulty: Easy]

题目：Findthetotalareacoveredbytworectilinearrectanglesina2Dplane.Eachrectangleisdefinedbyitsbottomleftcornerandtoprightcornerasshowninthefigure.Assumethatthetotalareaisneverbeyondthemaximumpossiblevalue

Lnho2015·2016-03-07 13:00

Leet Code OJ 172. Factorial Trailing Zeroes [Difficulty: Easy]

题目：Givenanintegern,returnthenumberoftrailingzeroesinn!.Note:Yoursolutionshouldbeinlogarithmictimecomplexity.翻译：给定一个整数n，返回n！末尾的0的个数。提示：你的解决方案应该运行在O（log(n)）的时间复杂度。分析：我们知道要形成一个末尾的0，需要组合出2和5这两个质因子。然而在n！中，

Lnho2015·2016-03-07 12:00

Leet Code OJ 172. Factorial Trailing Zeroes [Difficulty: Easy]

题目：Givenanintegern,returnthenumberoftrailingzeroesinn!.Note:Yoursolutionshouldbeinlogarithmictimecomplexity.翻译：给定一个整数n，返回n！末尾的0的个数。提示：你的解决方案应该运行在O（log(n)）的时间复杂度。分析：我们知道要形成一个末尾的0，需要组合出2和5这两个质因子。然而在n！中，

Lnho2015·2016-03-07 12:00

Leet Code OJ 189. Rotate Array [Difficulty: Easy]

题目：Rotateanarrayofnelementstotherightbyksteps.Forexample,withn=7andk=3,thearray[1,2,3,4,5,6,7]isrotatedto[5,6,7,1,2,3,4].Note:Trytocomeupasmanysolutionsasyoucan,thereareatleast3differentwaystosolvethi

Lnho2015·2016-03-05 23:00

Leet Code OJ 328. Odd Even Linked List [Difficulty: Easy]

题目：Givenasinglylinkedlist,groupalloddnodestogetherfollowedbytheevennodes.Pleasenoteherewearetalkingaboutthenodenumberandnotthevalueinthenodes.Youshouldtrytodoitinplace.TheprogramshouldruninO(1)spaceco

Lnho2015·2016-03-05 21:00

Leet Code OJ 328. Odd Even Linked List [Difficulty: Easy]

题目：Givenasinglylinkedlist,groupalloddnodestogetherfollowedbytheevennodes.Pleasenoteherewearetalkingaboutthenodenumberandnotthevalueinthenodes.Youshouldtrytodoitinplace.TheprogramshouldruninO(1)spaceco

Lnho2015·2016-03-05 21:00

Leet Code OJ 268. Missing Number [Difficulty: Easy]

题目：Givenanarraycontainingndistinctnumberstakenfrom0,1,2,…,n,findtheonethatismissingfromthearray.Forexample,Givennums=[0,1,3]return2.Note:Youralgorithmshouldruninlinearruntimecomplexity.Couldyouimpleme

Lnho2015·2016-03-04 18:00

Leet Code OJ 268. Missing Number [Difficulty: Easy]

题目：Givenanarraycontainingndistinctnumberstakenfrom0,1,2,…,n,findtheonethatismissingfromthearray.Forexample,Givennums=[0,1,3]return2.Note:Youralgorithmshouldruninlinearruntimecomplexity.Couldyouimpleme

Lnho2015·2016-03-04 18:00

Leet Code OJ 66. Plus One [Difficulty: Easy]

题目:Givenanon-negativenumberrepresentedasanarrayofdigits,plusonetothenumber.Thedigitsarestoredsuchthatthemostsignificantdigitisattheheadofthelist.翻译：给定一个非负数，它是有数字的数组组成，把这个非负数+1。这个非负数的存储方式，是把最高有效位数字放到列表

Lnho2015·2016-03-04 16:00

Leet Code OJ 66. Plus One [Difficulty: Easy]

题目:Givenanon-negativenumberrepresentedasanarrayofdigits,plusonetothenumber.Thedigitsarestoredsuchthatthemostsignificantdigitisattheheadofthelist.翻译：给定一个非负数，它是有数字的数组组成，把这个非负数+1。这个非负数的存储方式，是把最高有效位数字放到列表

Lnho2015·2016-03-04 16:00

Leet Code OJ 58. Length of Last Word [Difficulty: Easy]

题目：Givenastringsconsistsofupper/lower-casealphabetsandemptyspacecharacters’‘,returnthelengthoflastwordinthestring.Ifthelastworddoesnotexist,return0.Note:Awordisdefinedasacharactersequenceconsistsofnon

Lnho2015·2016-03-04 13:00

Leet Code OJ 58. Length of Last Word [Difficulty: Easy]

题目：Givenastringsconsistsofupper/lower-casealphabetsandemptyspacecharacters’‘,returnthelengthoflastwordinthestring.Ifthelastworddoesnotexist,return0.Note:Awordisdefinedasacharactersequenceconsistsofnon

Lnho2015·2016-03-04 13:00

Leet Code OJ 27. Remove Element [Difficulty: Easy]

题目：Givenanarrayandavalue,removeallinstancesofthatvalueinplaceandreturnthenewlength.Theorderofelementscanbechanged.Itdoesn’tmatterwhatyouleavebeyondthenewlength.翻译：给定一个数组和一个值，在原地移除所有的这个值的实例，并且返回新的数组长度。

Lnho2015·2016-03-04 13:00

Leet Code OJ 27. Remove Element [Difficulty: Easy]

题目：Givenanarrayandavalue,removeallinstancesofthatvalueinplaceandreturnthenewlength.Theorderofelementscanbechanged.Itdoesn’tmatterwhatyouleavebeyondthenewlength.翻译：给定一个数组和一个值，在原地移除所有的这个值的实例，并且返回新的数组长度。

Lnho2015·2016-03-04 13:00

Leet Code OJ 83. Remove Duplicates from Sorted List [Difficulty: Easy]

题目：Givenasortedlinkedlist,deleteallduplicatessuchthateachelementappearonlyonce.Forexample,Given1->1->2,return1->2.Given1->1->2->3->3,return1->2->3.翻译：给定一个排序号的链表，删除所有的重复元素，保证每个元素只出现一次。分析:在当前节点删除下一节点，会比

Lnho2015·2016-03-04 13:00

Leet Code OJ 21. Merge Two Sorted Lists [Difficulty: Easy]

题目:Mergetwosortedlinkedlistsandreturnitasanewlist.Thenewlistshouldbemadebysplicingtogetherthenodesofthefirsttwolists.翻译:合并2个已经排序的链表，并且返回一个新的链表。这个新的链表应该由前面提到的2个链表的节点所组成。分析：注意头节点的处理，和链表结束（next为null）的处理。

Lnho2015·2016-03-04 13:00

Leet Code OJ 21. Merge Two Sorted Lists [Difficulty: Easy]

题目:Mergetwosortedlinkedlistsandreturnitasanewlist.Thenewlistshouldbemadebysplicingtogetherthenodesofthefirsttwolists.翻译:合并2个已经排序的链表，并且返回一个新的链表。这个新的链表应该由前面提到的2个链表的节点所组成。分析：注意头节点的处理，和链表结束（next为null）的处理。

Lnho2015·2016-03-04 13:00

Leet Code OJ 206. Reverse Linked List [Difficulty: Easy]

题目：Reverseasinglylinkedlist.Hint:Alinkedlistcanbereversedeitheriterativelyorrecursively.Couldyouimplementboth?翻译：反转一个单链表。分析:可以先尝试通过简单例子画图分析，来弄清如何修改指向。代码:/***Definitionforsingly-linkedlist.*publicclass

Lnho2015·2016-03-03 20:00

Leet Code OJ 7. Reverse Integer [Difficulty: Easy]

题目：Reversedigitsofaninteger.Example1:x=123,return321Example2:x=-123,return-321Haveyouthoughtaboutthis?Herearesomegoodquestionstoaskbeforecoding.Bonuspointsforyouifyouhavealreadythoughtthroughthis!Ifth

Lnho2015·2016-03-03 16:00

Leet Code OJ 38. Count and Say [Difficulty: Easy]

题目：Thecount-and-saysequenceisthesequenceofintegersbeginningasfollows:1,11,21,1211,111221,…1isreadoffas“one1”or11.11isreadoffas“two1s”or21.21isreadoffas“one2,thenone1”or1211.Givenanintegern,generatethe

Lnho2015·2016-03-03 13:00

Leet Code OJ 38. Count and Say [Difficulty: Easy]

题目：Thecount-and-saysequenceisthesequenceofintegersbeginningasfollows:1,11,21,1211,111221,…1isreadoffas“one1”or11.11isreadoffas“two1s”or21.21isreadoffas“one2,thenone1”or1211.Givenanintegern,generatethe

Lnho2015·2016-03-03 13:00

Leet Code OJ 168. Excel Sheet Column Title [Difficulty: Easy]

题目：Givenapositiveinteger,returnitscorrespondingcolumntitleasappearinanExcelsheet.Forexample:1->A 2->B 3->C ... 26->Z 27->AA 28->AB 翻译：给定一个正数，返回它类似Excle中对应的列标题。分析：关联问题：“ExcelSheetColumnNumber”实际为10进制转2

Lnho2015·2016-03-03 13:00

Leet Code OJ 168. Excel Sheet Column Title [Difficulty: Easy]

题目：Givenapositiveinteger,returnitscorrespondingcolumntitleasappearinanExcelsheet.Forexample:1->A 2->B 3->C ... 26->Z 27->AA 28->AB 翻译：给定一个正数，返回它类似Excle中对应的列标题。分析：关联问题：“ExcelSheetColumnNumber”实际为10进制转2

Lnho2015·2016-03-03 13:00

Leet Code OJ 171. Excel Sheet Column Number [Difficulty: Easy]

Lnho2015·2016-03-03 12:00

Leet Code OJ 171. Excel Sheet Column Number [Difficulty: Easy]

Lnho2015·2016-03-03 12:00

Leet Code OJ 237. Delete Node in a Linked List [Difficulty: Easy]

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

Lnho2015·2016-03-02 11:00

Leet Code OJ 237. Delete Node in a Linked List [Difficulty: Easy]

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

Lnho2015·2016-03-02 11:00

Leet Code OJ 112. Path Sum [Difficulty: Easy]

题目:Givenabinarytreeandasum,determineifthetreehasaroot-to-leafpathsuchthataddingupallthevaluesalongthepathequalsthegivensum.Forexample:Giventhebelowbinarytreeandsum=22,returntrue,asthereexistaroot-to-l

Lnho2015·2016-02-29 19:00

Leet Code OJ 101. Symmetric Tree [Difficulty: Easy]

题目：Givenabinarytree,checkwhetheritisamirrorofitself(ie,symmetricarounditscenter).Forexample,thisbinarytreeissymmetric:Butthefollowingisnot:Note:Bonuspointsifyoucouldsolveitbothrecursivelyanditerativel

Lnho2015·2016-02-29 17:00

Leet Code OJ 202. Happy Number [Difficulty: Easy]

题目：Writeanalgorithmtodetermineifanumberis“happy”.Ahappynumberisanumberdefinedbythefollowingprocess:Startingwithanypositiveinteger,replacethenumberbythesumofthesquaresofitsdigits,andrepeattheprocessunt

Lnho2015·2016-02-27 18:00

Leet Code OJ 202. Happy Number [Difficulty: Easy]

题目：Writeanalgorithmtodetermineifanumberis“happy”.Ahappynumberisanumberdefinedbythefollowingprocess:Startingwithanypositiveinteger,replacethenumberbythesumofthesquaresofitsdigits,andrepeattheprocessunt

Lnho2015·2016-02-27 18:00

Leet Code OJ 70. Climbing Stairs [Difficulty: Easy]

题目：Youareclimbingastaircase.Ittakesnstepstoreachtothetop.Eachtimeyoucaneitherclimb1or2steps.Inhowmanydistinctwayscanyouclimbtothetop?翻译：你在爬一个楼梯。到达顶部有n级阶梯。每次你可以选择爬一级或者二级。在多少不同的方式去到达顶部？分析：当n=1，无疑只有一种方式，

Lnho2015·2016-02-27 17:00

Leet Code OJ 70. Climbing Stairs [Difficulty: Easy]

题目：Youareclimbingastaircase.Ittakesnstepstoreachtothetop.Eachtimeyoucaneitherclimb1or2steps.Inhowmanydistinctwayscanyouclimbtothetop?翻译：你在爬一个楼梯。到达顶部有n级阶梯。每次你可以选择爬一级或者二级。在多少不同的方式去到达顶部？分析：当n=1，无疑只有一种方式，

Lnho2015·2016-02-27 17:00

Leet Code OJ 100. Same Tree [Difficulty: Easy]

题目：Giventwobinarytrees,writeafunctiontocheckiftheyareequalornot.Twobinarytreesareconsideredequaliftheyarestructurallyidenticalandthenodeshavethesamevalue.翻译：给2个二叉树，写一个程序去检验它们是否“相同”。如果2个二叉树的结构相同，并且它们的节

Lnho2015·2016-02-27 17:00

Leet Code OJ 100. Same Tree [Difficulty: Easy]

题目：Giventwobinarytrees,writeafunctiontocheckiftheyareequalornot.Twobinarytreesareconsideredequaliftheyarestructurallyidenticalandthenodeshavethesamevalue.翻译：给2个二叉树，写一个程序去检验它们是否“相同”。如果2个二叉树的结构相同，并且它们的节

Lnho2015·2016-02-27 17:00

Leet Code OJ 263. Ugly Number [Difficulty: Easy]

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

Lnho2015·2016-02-27 17:00

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leet

Leet Code OJ 110. Balanced Binary Tree [Difficulty: Easy]

Leet Code OJ 1. Two Sum [Difficulty: Easy]

Leet Code OJ 191. Number of 1 Bits [Difficulty: Easy]

Leet Code OJ 191. Number of 1 Bits [Difficulty: Easy]

Leet-code144. Binary Tree Preorder Traversal

Leet Code OJ 260. Single Number III [Difficulty: Medium]

Leet Code OJ 102. Binary Tree Level Order Traversal [Difficulty: Easy]

leetcode 139. Word Break

Leet Code OJ 26. Remove Duplicates from Sorted Array [Difficulty: Easy]

Leet Code OJ 26. Remove Duplicates from Sorted Array [Difficulty: Easy]

Leet Code OJ 326. Power of Three [Difficulty: Easy]

Leet Code OJ 219. Contains Duplicate II [Difficulty: Easy]

Leet Code OJ 235. Lowest Common Ancestor of a Binary Search Tree [Difficulty: Easy]

Leet Code OJ 235. Lowest Common Ancestor of a Binary Search Tree [Difficulty: Easy]

Leet Code OJ 223. Rectangle Area [Difficulty: Easy]

Leet Code OJ 172. Factorial Trailing Zeroes [Difficulty: Easy]

Leet Code OJ 172. Factorial Trailing Zeroes [Difficulty: Easy]

Leet Code OJ 189. Rotate Array [Difficulty: Easy]

Leet Code OJ 328. Odd Even Linked List [Difficulty: Easy]

Leet Code OJ 328. Odd Even Linked List [Difficulty: Easy]

Leet Code OJ 268. Missing Number [Difficulty: Easy]

Leet Code OJ 268. Missing Number [Difficulty: Easy]

Leet Code OJ 66. Plus One [Difficulty: Easy]

Leet Code OJ 66. Plus One [Difficulty: Easy]

Leet Code OJ 58. Length of Last Word [Difficulty: Easy]

Leet Code OJ 58. Length of Last Word [Difficulty: Easy]

Leet Code OJ 27. Remove Element [Difficulty: Easy]

Leet Code OJ 27. Remove Element [Difficulty: Easy]

Leet Code OJ 83. Remove Duplicates from Sorted List [Difficulty: Easy]

Leet Code OJ 21. Merge Two Sorted Lists [Difficulty: Easy]

Leet Code OJ 21. Merge Two Sorted Lists [Difficulty: Easy]

Leet Code OJ 206. Reverse Linked List [Difficulty: Easy]

Leet Code OJ 7. Reverse Integer [Difficulty: Easy]

Leet Code OJ 38. Count and Say [Difficulty: Easy]

Leet Code OJ 38. Count and Say [Difficulty: Easy]

Leet Code OJ 168. Excel Sheet Column Title [Difficulty: Easy]

Leet Code OJ 168. Excel Sheet Column Title [Difficulty: Easy]

Leet Code OJ 171. Excel Sheet Column Number [Difficulty: Easy]

Leet Code OJ 171. Excel Sheet Column Number [Difficulty: Easy]

Leet Code OJ 237. Delete Node in a Linked List [Difficulty: Easy]

Leet Code OJ 237. Delete Node in a Linked List [Difficulty: Easy]

Leet Code OJ 112. Path Sum [Difficulty: Easy]

Leet Code OJ 101. Symmetric Tree [Difficulty: Easy]

Leet Code OJ 202. Happy Number [Difficulty: Easy]

Leet Code OJ 202. Happy Number [Difficulty: Easy]

Leet Code OJ 70. Climbing Stairs [Difficulty: Easy]

Leet Code OJ 70. Climbing Stairs [Difficulty: Easy]

Leet Code OJ 100. Same Tree [Difficulty: Easy]

Leet Code OJ 100. Same Tree [Difficulty: Easy]

Leet Code OJ 263. Ugly Number [Difficulty: Easy]