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LeetCode 15. 3Sum题目描述：Given an array nums of n integers, are there elements a, b, c in nums such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero. Note:...

LeetCode 873. Length of Longest Fibonacci Subsequence题目描述：A sequence X_1, X_2, …, X_n is fibonacci-like if:n >= 3X_i + X_{i+1} = X_{i+2} for all i + 2 <= nGiven a strictly increasi...

LeetCode 22. Generate Parentheses题目描述：Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.For example, given n = 3, a solution set is:[ ...

LeetCode 131. Palindrome PartitioningGiven a string s, partition s such that every substring of the partition is a palindrome.Return all possible palindrome partitioning of s.Example:Input...

LeetCode 48. Rotate ImageYou are given an n x n 2D matrix representing an image.Rotate the image by 90 degrees (clockwise).Note:You have to rotate the image in-place, which means you have ...

LeetCode 24. Swap Nodes in Pairs题目描述：Given a linked list, swap every two adjacent nodes and return its head.Example:Given 1->2->3->4, you should return the list as 2->1->4...

leetcode 10 Regular Expression Matching题目描述：Given an input string (s) and a pattern (p), implement regular expression matching with support for ‘.’ and ‘*’.‘.’ Matches any single character. ...

LeetCode 46. Permutations题目描述：Given a collection of distinct integers, return all possible permutations.Example:Input: [1,2,3]Output:[ [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2]...

LeetCode 23. Merge k Sorted Lists题目描述：Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.Example:Input:[ 1->4->5, 1->3->4, ...

LeetCode 25. Reverse Nodes in k-Group题目描述：Given a linked list, reverse the nodes of a linked list k at a time and return its modified list.k is a positive integer and is less than or equal t...

题目描述：You are given a string, s, and a list of words, words, that are all of the same length. Find all starting indices of substring(s) in s that is a concatenation of each word in words exactly once ...

题目描述：Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.If such arrangement is not possible, it must rearrange it as the lowest possi...

LeetCode 91. Decode WaysA message containing letters from A-Z is being encoded to numbers using the following mapping:'A' -> 1'B' -> 2...'Z' -> 26Given a non-empty string contain...

LeetCode 2. Add Two Numbers题目描述：You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single...

LeetCode 65. Valid Number题目描述：Validate if a given string is numeric.Some examples:"0" => true" 0.1 " => true"abc" => false"1 a" => false"2e10" => trueNot

LeetCode 73. Set Matrix Zeroes题目描述：Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in-place.Example 1:Input: [ [1,1,1], [1,0,1], [1,1,1]]Outp...

LeetCode 21 Merge Two Sorted Lists题目描述： Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists. 翻译： 将两个已经排...

26. Remove Duplicates from Sorted Array题目描述：Given a sorted array nums, remove the duplicates in-place such that each element appear only once and return the new length. Do not allocate extra s...

27. Remove Element跟26题类似，没什么营养 在重新确定数组长度时，除了erase还可以用base迭代器和resize函数操作以下，即直接nums.resize(base)class Solution {public: int removeElement(vector<int>& nums, int val) { ...

28. Implement strStr()题目描述：Implement strStr(). Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.Example 1:Input: haystack = "hello",...

38. Count and Say题目描述：The count-and-say sequence is the sequence of integers with the first five terms as following:1. 12. 113. 214. 12115. 1112211 is read off as...

LeetCode 98. Validate Binary Search Tree题目描述：Given a binary tree, determine if it is a valid binary search tree (BST).Assume a BST is defined as follows:The left subtree of a node contains...

LeetCode 8. String to Integer (atoi)题目描述：Implement atoi which converts a string to an integer.The function first discards as many whitespace characters as necessary until the first non-white...

题目描述：Given two words (beginWord and endWord), and a dictionary’s word list, find the length of shortest transformation sequence from beginWord to endWord, such that:Only one letter can be changed ...

深度优先搜索(Depth First Search)和广度优先搜索(Breadth First Search)深度优先遍历图的方法是，从图中某顶点v出发（百度百科）： （1）访问顶点v； （2）依次从v的未被访问的邻接点出发，对图进行深度优先遍历；直至图中和v有路径相通的顶点都被访问； （3）若此时图中尚有顶点未被访问，则从一个未被访问的顶点出发，重新进行深度优先遍历，直到图中所...