[LeetCode 202] Happy Number

标签：java   算法   leetcode   

题目链接：happy-number

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) {
    	Set<Integer> s = new HashSet<Integer>();
    	while(n != 1) {
    		int sum = 0;
    		while(n != 0) {
    			int mod = n % 10;
            	sum += mod * mod;
            	n /= 10;
    		}
    		if(s.contains(sum))
    			return false;
    		s.add(n = sum);
        }
    	return true;     
    }
}

[LeetCode 202] Happy Number

标签：java   算法   leetcode   

原文地址：http://blog.csdn.net/ever223/article/details/45286227