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Symmetric TreeGiven a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For example, this binary tree is symmetric... 阅读全文
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Gas StationThere areNgas stations along a circular route, where the amount of gas at stationiisgas[i].You have a car with an unlimited gas tank and it... 阅读全文
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Intersection of Two Linked ListsWrite a program to find the node at which the intersection of two singly linked lists begins.For example, the followin... 阅读全文
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Longest Substring Without Repeating CharactersGiven a string, find the length of the longest substring without repeating characters. For example, the ... 阅读全文
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Word LadderTotal Accepted:24823Total Submissions:135014My SubmissionsGiven two words (startandend), and a dictionary, find the length of shortest tran... 阅读全文
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Search Insert PositionGiven a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if ... 阅读全文
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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 fir... 阅读全文
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Validate Binary Search TreeGiven a binary tree, determine if it is a valid binary search tree (BST).Assume a BST is defined as follows:The left subtre... 阅读全文
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Add BinaryGiven two binary strings, return their sum (also a binary string).For example,a ="11"b ="1"Return"100".Hide TagsMathString先补全字符串，从末尾开始加，每次计算... 阅读全文
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Search a 2D MatrixWrite an efficient algorithm that searches for a value in anmxnmatrix. This matrix has the following properties:Integers in each row... 阅读全文
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Find Peak ElementA peak element is an element that is greater than its neighbors.Given an input array wherenum[i] ≠ num[i+1], find a peak element and ... 阅读全文
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Unique Binary Search TreesGivenn, how many structurally uniqueBST's(binary search trees) that store values 1...n?For example,Givenn= 3, there are a to... 阅读全文
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Compare Version NumbersCompare two version numbersversion1andversion1.Ifversion1>version2return 1, ifversion1 22; return 1.Example2: version1=="11.22.... 阅读全文
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AnagramsGiven an array of strings, return all groups of strings that are anagrams.Note: All inputs will be in lower-case.Anagrams：即字母个数和字母都相同，但是字母顺序不相... 阅读全文
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ZigZag ConversionThe string"PAYPALISHIRING"is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern i... 阅读全文