202_HappyNumber

题目：Write an algorithm to determine if a number is "happy".

A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1. Those numbers for which this process ends in 1 are happy numbers.

Example: 19 is a happy number

• 12 + 92 = 82
• 82 + 22 = 68
• 62 + 82 = 100

• 12 + 02 + 02 = 1

思想：将数字拆开以字符形式存储再计算，注意采用map的方式记录数据是否重复

代码：

class Solution {public:string Number(int n){//将数字转换成字符串string str= "";int r, s;while (n>0){r = n % 10;s = n / 10;n = s;str += r;}return str;}bool isHappy(int n) {map<int, bool>mymap;//采用map记录数字是否循环string str;if (n <= 0)return false;while (n!=1){if (!mymap[n]){mymap[n] = true;str = Number(n);int sum = 0;for (int i = 0; i < str.size(); i++){sum += str[i] * str[i];}n = sum;}else{break;}}if (n==1){return true;}else{return false;}}};