题目: Given an unsorted integer array, find the first missing positive integer. For example,Given [1,2,0] return 3,and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. 代码: class Solution { public: int firstMissingPos…
题目: Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each number in C may only be used once in the combination. Note: All numbers (including target) will be…
题目: Given 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 it were inserted in order. You may assume no duplicates in the array. Here are few examples.[1,3,5,6], 5 → 2[1,3,5,6],…
题目: Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array. Note:You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold additional elements from nums2. The number of elements i…
题目: Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example:Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ / \ 7 2 5 1 return [ [5,4,11,2], [5,8,4,5] ] 代码: /** * Defini…
题目: Write a function to find the longest common prefix string amongst an array of strings. 代码: class Solution { public: string longestCommonPrefix(vector<string>& strs) { ) return ""; std::]; ; i < strs.size(); ++i ) { size_t j = ;…
题目: Implement regular expression matching with support for '.' and '*'. '.' Matches any single character. '*' Matches zero or more of the preceding element. The matching should cover the entire input string (not partial). The function prototype shoul…
题目: Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring. 代码: class Solution { public: string longestPalindrome(string s) { const…
题目: Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring. For "(()", the longest valid parentheses substring is "()", which has length = 2. Another example…
题目: The count-and-say sequence is the sequence of integers beginning as follows:1, 11, 21, 1211, 111221, ... 1 is read off as "one 1" or 11.11 is read off as "two 1s" or 21.21 is read off as "one 2, then one 1" or 1211. Given…
题目: Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999. 代码: class Solution { public: int romanToInt(string s) { ; std::map<char, int> symbol_value; char symbol_ori[size] = {'M','D','C','L','X',…
题目: Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999. 代码: class Solution { public: string intToRoman(int num) { ) return NULL; ; std::string symbol_ori[size] = {"M","D","C&…
题目: Given an integer, write a function to determine if it is a power of two. 代码: class Solution { public: bool isPowerOfTwo(int n) { ) return false; ; ; i< && countOne<=; ++i ) { countOne += (n>>i) & ; } ; } }; tips: 首先的思路是bit-muni…
题目: Invert Binary Tree Total Accepted: 20346 Total Submissions: 57084My Submissions Question Solution Invert a binary tree. 4 / \ 2 7 / \ / \ 1 3 6 9 to 4 / \ 7 2 / \ / \ 9 6 3 1 Trivia:This problem was inspired by this original tweet by Max Howell:…
题目: Given a binary tree, determine if it is height-balanced. For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1. 代码: /** * Definition for a bina…
题目: Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order. For example,Given n = 3, You should return the following matrix: [ [ 1, 2, 3 ], [ 8, 9, 4 ], [ 7, 6, 5 ] ] 代码: class Solution { public: vector<vector<…
题目: Given numRows, generate the first numRows of Pascal's triangle. For example, given numRows = 5,Return [ [1], [1,1], [1,2,1], [1,3,3,1], [1,4,6,4,1] ] 代码: class Solution { public: vector<vector<int>> generate(int numRows) { vector<vector…
题目: Given a string s and a dictionary of words dict, add spaces in s to construct a sentence where each word is a valid dictionary word. Return all such possible sentences. For example, givens = "catsanddog",dict = ["cat", "cats&q…
题目: Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path. Note: You can only move either down or right at any point in time. 代码: class Solution { public:…
题目: Given a string s, partition s such that every substring of the partition is a palindrome. Return the minimum cuts needed for a palindrome partitioning of s. For example, given s = "aab",Return 1 since the palindrome partitioning ["aa&qu…
题目: Given an array of non-negative integers, you are initially positioned at the first index of the array. Each element in the array represents your maximum jump length at that position. Your goal is to reach the last index in the minimum number of j…
题目: Given a string containing only digits, restore it by returning all possible valid IP address combinations. For example:Given "25525511135", return ["255.255.11.135", "255.255.111.35"]. (Order does not matter) 代码: class So…
题目: Follow up for "Unique Paths": Now consider if some obstacles are added to the grids. How many unique paths would there be? An obstacle and empty space is marked as 1 and 0 respectively in the grid. For example, There is one obstacle in the m…
题目: Given two words (start and end), and a dictionary, find all shortest transformation sequence(s) from start to end, such that: Only one letter can be changed at a time Each intermediate word must exist in the dictionary For example, Given:start = …
题目: Given a linked list, determine if it has a cycle in it. Follow up:Can you solve it without using extra space? 代码: 用hashmap版 /** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next…
题目: Given an array of integers, every element appears three times except for one. Find that single one. Note:Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory? 代码: class Solution { public: int s…
题目: Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place. click to show follow up. Follow up: Did you use extra space?A straight forward solution using O(mn) space is probably a bad idea.A simple improvement us…
