LEETCODE-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

还没有看到哈希表，在这里用了一个偷懒的方法——用i去记录相加的次数，如果次数太多则认定为false；
等看完哈希表再来完善

class Solution {
public:
    bool isHappy(int n) {
        int i = 0;
    while (1) {
        int sum = 0;
        while (n != 0) {
            int x = n % 10;
            sum = sum + x * x;
            n = n / 10;
        }
        n = sum;
        if (n == 1)
            return 1;
        else
            i++;
        if (i == 25)
            return 0;
    }
    }
};