package com.abhishek.dojo;

import java.util.HashSet;

/*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:

Input: 19
Output: true
Explanation:
12 + 92 = 82
82 + 22 = 68
62 + 82 = 100
12 + 02 + 02 = 1
*/

class FindHappyNumber {
    public boolean isHappy(int n) {
        HashSet<Integer> set = new HashSet<Integer>();
        // loop will terminate once we start seeing original number cycle again
        while (!set.contains(n)){
            set.add(n);
            n = getSum(n);
            if(n == 1){
                return true;
            }
        }
        return false;
    }

    //quick way to get of squares of a number
    public int getSum(int n){
        int sum =0;
        while (n>0){
            sum += (n%10) * (n%10);
            n = n/10;
        }
        return sum;
    }
}