LeetCodecpp最新中文题解.pdfLeetCodecpp最新中文题解.pdfLeetCodecpp最新中文题解.pdf目录3.4Addbinary615.1.5BinaryTreeLevelOr-3.5LongestPalindromicSubstring.62dertraversalil3.6RegularExpressionMatching665.1.6BinaryTreeZigzag3.7WildcardMatching67LevelOrdertraversal.963.8LongestCommonPrefix5.1.7RecoverBinarySearch3.9ValidNumber70Tree983.10Integertoroman725.1.8SameTree3.11RomantoInteger735.1.9SymmetricTree1003.12CountandSay745.1.10BalancedBinaryTree..1023.13Anagrams755.1.11FlattenBinaryTreeto3.14SimplifyPath76LinkedList1033.15LengthofLastWord775.1.12PopulatingNextRightPointersineachnodeii105第4章栈和队列7952二叉树的构建10641栈795.2.1ConstructBinaryTree4ValidParentheses79fromPreorderandIn4.1.2LongestvalidParenorderTraversa106theses805.2.2ConstructBinaryTree4.1.3LargestRectangleinfromInorderandposHistogram82torderTraversal1074.1.4Evaluatereversepol-53二叉查找树108ishnotation845.3.1UniqueBinarySearch4.2队列85Trees.1085.3.2UniqueBinarySearch第5章树86Treesli.1105.1二叉树的遍历865.3.3ValidateBinarySearch5.1.1BinaryTreePreorderTreeTraversal865.3.4ConvertSortedarrayto5.1.2BinaryTreeInorderBinarySearchTree...112Traversal885.3.5ConvertSortedListto5.1.3BinaryTreePostorderBinarySearchTree113Traversal9054二叉树的递归.1145.1.4BinaryTreeLevelOr5.4.1MinimumDepthofBidertraversal)2narylree115目录5.4.2MaximumDepthofBi8.3.,2重新实现nextpermunaryTree116tation1425.4.3PathSum11783.3递归.1435.44PathSumil1188.4PermutationsII1445.4.5BinaryTreeMaximum8.4.1nextpermutation...144PathSuum11984.2重新实现nextpermu5.4.6PopulatingNextRighttation144Pointersineachnode120843递归1445.4.7SumRoottoLeafnum8.5Combinations146bers2185.1递归1468.5.2迭代147第6章排序1238.6LetterCombinationsofaphone6.1MergeSortedArray123umber1476.2MergeTwoSortedLists12486.1递归1486.3MergekSortedLists124862迭代96.4InsertionSortList125第9章广度优先搜索1506.5Sortlist1269.1WordLadder1506.6FirstMissingPositive1279.2WordLadderil1546.7SortColors1289.3Surroundedregions162第7章查找94小结16413194.l适用场景1647.1Searchforarange131942思考的步骤7.2SearchInsertPosition.13294.3代码模板1657.3Searcha2DMatrix133第10章深度优先搜索173第8章暴力枚举法13510.1PalindromePartitioning1738.1Subsets13510.2UniquePaths1768.1.1递归1350.2.1深搜1768.1.2迭代.1371022备忘录法.1768.2Subsetsil13810.23动规177821递归13810.24数学公式1788.2.2迭代.14110.3UniquePathsIl1798.3Permutations14210.3.1备忘录法1798.3.1nextpermutation14210.3.2动规.180目录10.4N-Queens1813.4Maximalrectangle21310.5N-QueensII18413.5BestTimetoBuyandSellStock10.6Restoreipaddresses186.21410.7CombinationSum18813.6InterleavingString21510.8CombinationSumIl18913.7ScrambleString21710.9GenerateParentheses.19013.8MinimumPathSum.22210.10Sudokusolver19213.9EditDistance22410.11WordSearch.19313.10DecodeWays.22610.12小结19513.11Distinctsub22710.12.1适用场景19513.12WordBreak22810.122思考的步骤1951313WordBreakil2300.12.3代码模板197第14章图23210.12.4深搜与回溯法的区別.19714.1CloneGraph23210.12.5深搜与递归的区别..197第15章细节实现题235第11章分治法19915.1ReverseInteger2351.1Pow(x,n)19915.2PalindromeNumber.23611.2Sqrt(x)20015.3InsertInterval237第12章贪心法20115.4MergeIntervals23812.1Jumpgame20115.5MinimumWindowSubstring23912.2JumpgameII15.6MultiplyStrings24112.3BestTimetobuyandSellstock20415.7SubstringwithConcatenation12.4BestTimetobuyandsellstockl205ofallwords24412.5LongestSubstringWithoutre15.8Pascal,sTriangle245peatingCharacters20615.9PascalsTriangleIl24612.6ContainerwithMostWater..20715.10SpiralMatrix24715.11SpiralmatrixII248第13章动态规划20915.12ZigZagConversion25013.1Triangle20915.13DivideTwoIntegers25113.2MaximumSubarray15.14TextJustification25313.3PalindromePartitioningII1215.15MaxPointsonaline255目录第1章编程技巧在判断两个浮点数a和b是否相等时,不要用a==b,应该判断二者之差的绝对值fabs(a-b)是否小于某个阈值,例如1e-9。
判断一个整数是否是为奇数,用x%2!=0,不要用x%2=1,因为ⅹ可能是负用char的值作为数组下标(例如,统计字符串中每个字符岀现的次数),要考虑到char可能是负数。
有的人考虑到了,先强制转型为unsignedint再用作下标,这仍然是错的。
正确的做法是,先强制转型为unsignedchar,再用作下标。
这涉及C十整型提升的规则,就不详述了。
以下是关于STL使用技巧的,很多条款来自《EffectiveSTL》这本书。
vector和string优先于动态分配的数组首先,在功能上,由于vector能够保证连续内存,因此一旦分配了后,它的功能跟原始数组相当;其次,如果用new,意味着你要确保后面进行孓delete,一旦忘记了,就会出现BUG,且这样需要都写一行delete,代码不够短再次,声明多维数组的话,只能一个一个new,例如int**ary=newint*[row_num];for(inti=0:i<rownum;++1)ary[i]newint[col_num]用vector的话一行代码搞定vector<vector<int>>ary(row_num,vector<int>(col_num,0))使用reserve来避免不必要的重新分配第2章线性表这类题目考察线性表的操作,例如,数组,单链表,双向链表等。
2数组2.1.1RemoveDuplicatesfromSortedarray描述Givenasortedarray,removetheduplicatesinplacesuchthateachelementappearonlyonceandreturnthenewlengthDonotallocateextraspaceforanotherarray,youmustdothisinplacewithconstantmemoryForexample,GiveninputarrayA=[1,1,2Yourfunctionshouldreturnlength=2,andaisnow[1,2]分析无代码1/LeetCode,RemoveDuplicatesfromSortedArray//时间复杂度0(n),空间复杂度0(1)classSolutiontublicintremoveDuplicates(vector<int>&nums)tif(numsemptyo)return0;intindex=ofor(inti=1:inumssize:1++iif(nums[index]!nums[i])nums[++index]=nums[i]returnindex12.1数组代码2//LeetCode,RemoveDuplicatesfromSortedArray/使用STL,时间复杂度0(n),空间复杂度0(1)classSolutionipublicintremoveDuplicates(vector<int>&nums)treturndistance(numsbegin(),unique(numsbegin(),numsend())代码3/LeetCode,RemoveDuplicatesfromSortedArray/使用STL,时间复杂度0(n),空间复杂度0(1)lassSolutionfublicintremoveDuplicates(vector<int>&nums)treturndistance(numsbegin(,removeDuplicates(numsbegin(,numsend(),numsbegintemplate<typenameInIt,typenameoutit>OutItremoveDuplicates(InItfirst,InItlast,OutItoutput)thile(firstlast)i*output++=*firstfirstupper_bound(first,last,*firstreturnoutput相关题目RemoveDuplicatesfromSortedArrayI,见§2.1.22.1.2RemoveDuplicatesfromSortedArrayII描述Followupfor"RemoveDuplicates"Whatifduplicatesareallowedatmosttwice?Forexample,Givensortedarraya=[1,1,1,2,2,3]Yourfunctionshouldreturnlength=5,andAisnow[1,1,2,2,3分析加一个变量记录一下元素出现的次数即可。
这题因为是已经排序的数组,所以一个变量即可解决。
如果是没有排序的数组,则需要引入一个hashmap来记录出现次数。
4第2章线性表代码1//LeetCode,RemoveDuplicatesfromSortedArrayII//时间复杂度0(n),空间复杂度0(1)//qauthorhex108(https://github.com/hex108)classSolutiontublicintremoveDuplicates(vector<int>&nums)tif(numssize(<=2)returnnumssizeintindex=2for(inti=2:inumssize(:i++)ff(nums[i]!numslindex-2]nums[index++]=nums[i]returnindex;代码2下面是一个更简洁的版本。
上面的代码略长,不过扩展性好一些,例如将occur<2改为occur3,就变成了允许重复最多3次。
//LeetCode,RemoveDuplicatesfromSortedArrayII7/@author虞航仲(http://weibo.com/u/1666779725)//时间复杂度0(n),空间复杂度0(1)lassSolutionfpublicintremoveDuplicates(vector<int>&nums)tconstintn=numssizeintindex=0:for(inti=0:i<n;++i)if(i>0&&i<n-1&nums[i]=nums[i-1]&nums[i]=nums[i1])continue;nums[index++]=nums[i]returnindex;相关题目RemoveDuplicatesfromSortedArray,见§2.1.1
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