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
public class Solution {
public boolean isHappy(int n) {
HashSet<Integer> hashSet = new HashSet<>();
while (n != 1) {
if (!hashSet.add(n)) {
return false;
}
char[] charArray = String.valueOf(n).toCharArray();
int sum = 0;
for (char c : charArray) {
sum += Math.pow(Integer.valueOf(c + ""), 2);
}
n = sum;
}
return true;
}
}