LeetCode : 202. Happy Number

[congr]

https://leetcode.com/problems/happy-number/

[congr]

class Solution {
    public boolean isHappy(int n) {
        Set<Integer> set = new HashSet();

        int s = 0;
        while (set.add(s)) {  // !!!! didn't contain s : true
            s = 0;            // !!!! initialize
            while (n != 0) {
                int k = n % 10;
                n = n / 10;
                s += k*k;
            }
            n = s; // loop endless
        }

        return s == 1;
    }
}