Jesus in my place

罗马字母规则见：https://zh.wikipedia.org/wiki/%E7%BD%97%E9%A9%AC%E6%95%B0%E5%AD%97因为相减减数只能是一位而且不能跨位数，相加同一个字母不能超过三个，所以可以先用一张对应表将相减能得到的数表示出来，并表述出4*10^n.class Solution {public: string intToRoman(int num

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent house

class TrieNode {public: // Initialize your data structure here. TrieNode() { val='0'; end_of_a_word=0; for(int i=0;i<26;i++) {

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.For example,Given 1->2->3->3->4->4->5, return 1->2->5.Given 1->1-

Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between).For example:Given binary

Solution 1:1. use merge2list(), and merge all lists one by one. Time complexity is O(n*longest list length)2. For each node, find the smallest node among all head nodes in O(k) time, Time complexi

1. 2Sum: hash Table O(n*n)2. 3Sum: 2Sum + 1 : O(n*n)for loop + 左右夹逼法：O（N＊N）class Solution {public:    vector > threeSum(vector &num) {        // Note: The Solution object is instantiated

羅馬數字共有7個，即I（1）、V（5）、X（10）、L（50）、C（100）、D（500）和M（1000）。按照下述的規則可以表示任意正整數。需要注意的是罗马数字中没有“0”，與進位制無關。一般認為羅馬數字只用來記數，而不作演算。重複數次：一個羅馬數字重複幾次，就表示這個數的幾倍。右加左減：在較大的羅馬數字的右邊記上較小的羅馬數字，表示大數字加小數字。在較大的羅馬數字的左邊

Say you have an array for which the ith element is the price of a given stock on day i.Design an algorithm to find the maximum profit. You may complete at most two transactions.Note:You

Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.OJ's undirected graph serialization:Nodes are labeled from 0 to N - 1, where N is the total nod

Given a 2D board containing 'X' and 'O', capture all regions surrounded by 'X'.A region is captured by flipping all 'O's into 'X's in that surrounded region .For example,X X X XX O O

Given a string s1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively.Below is one possible representation of s1 = "great": great / \ gr

Given preorder and inorder traversal of a tree, construct the binary tree.Note:You may assume that duplicates do not exist in the tree.class Solution {public: TreeNode *buildTree(vector

Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers on the row below.For example, given the following triangle[ [2], [3,4], [

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 "()",

Given a linked list, swap every two adjacent nodes and return its head.For example,Given 1->2->3->4, you should return the list as 2->1->4->3.Your algorithm should use only constant space.

Given a string S and a string T, count the number of distinct subsequences of T in S.A subsequence of a string is a new string which is formed from the original string by deleting some (can be non