#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

构成群

4

bool isHappy(int n) {
if (n <= 0) return false;

int magic = 4;
while (1) {
if (n == 1) return true;
if (n == magic) return false;
int t = 0;
while (n) {
t += (n % 10) * (n % 10);
n /= 10;
}
n = t;
}
}