【LeetCode】202 - Happy Number

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

Solution: 辅助函数；循环计算每位数字的平方和，直到出现结果为1(返回true)或者重复(返回false)

 class Solution {
 public:
     bool isHappy(int n) {
         map<int,bool> m;
         int ret=sum(n);
         while(ret!=){
             if(m[ret]==true)return false;
             m[ret]=true;
             ret=sum(ret);
         }
         return true;
     }
     int sum(int n){
         int ret=;
         while(n){
             ret += (n%)*(n%);   //不支持（n%10)^2
             n /= ;
         }
         return ret;
     }
 };