/*

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

*/

import java.util.HashSet;

public class isHappy{

public static boolean isHappy(int n) {

HashSet<Integer> s = new HashSet<Integer>();

while(s.add(n)) {

int sum = 0;

while (n > 0) {

sum += Math.pow(n%10, 2);

n = n / 10;

}

if (sum == 1) return true;

else {

n = sum;

}

}

return false;

}

public static void main(String[] args) {

System.out.print(isHappy(140));

}

}