202.Happy Number

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

代码：
import java.util.HashSet;

import java.util.Set;

public class Solution {

    public boolean isHappy(int n) {

    Set<Integer> set = new HashSet<Integer>();
//用set判断是否有循环，如果循环就退出

    while(!set.contains(n)){

    set.add(n);

    n = calcute(n);

    if(n==1)

    return true;

    }

    return false ;

    }


//计算每位数的平方和

    public int calcute(int n){

    int []a = new int[10];

         int i = 0 ;

         int result = 0 ;

        while(n>0){

      a[i] = n%10;

      n = n/10;

      i++;

      }

     

      for(int k=0 ;k<i;k++){

      result += a[k]*a[k] ;

      }

     return result ;

    }

}