[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

Credits:
Special thanks to @mithmatt and @ts for adding this problem and creating all test cases.

新出的easy的题目。

class Solution {
public:
    bool isHappy(int n) {
        int tmp, dig;
        while (n != 4) {
            tmp = 0;
            while (n > 0) {
                dig = n % 10;
                tmp += dig * dig;
                n /= 10;
            }
            n = tmp;
            if (n == 1) return true;
        }
        return false;
    }
};