Happy Number

题目描述：

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

这个题算是最近碰到的最简单的了，一次搞定、

代码如下：

public class Solution {
    public boolean isHappy(int n) {
        Set<Integer> set=new HashSet<Integer>();
        set.add(n);
        while(n!=1){
        	int result=0;
        	while(n!=0){
        		int reminder=n%10;
        		n=n/10;
        		result+=reminder*reminder;
        	}
        	n=result;
        	if(set.contains(n))
        		return false;
        	set.add(n);
        }
        return true;
    }
}