### 问题描述

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



### 代码

class Solution {
public:

bool isHappy(int n) {
set<int> elems;
int t = n;
while(t) {
if(t==1) break;
int i = 0;
int j = t;
while(j) {
i+= (j%10)*(j%10);
j/=10;
}
t = i;
if(elems.find(t)!=elems.end()) {
return false;
}
elems.insert(t);
}
return true;
}
}