Leetcode#202Happy Number

标签：determine   positive   following   include   replace   

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

问题分析，难点如何识别出计算链条出现loop，此处采用的hash的方法

public class Solution {

    public boolean isHappy(int n) {

        Map<Integer,Integer> p=new HashMap<Integer,Integer>();

        int m=n;

        int sm=0;

        while(m>1)

        {

            sm=m;

            int x=0;

            while(m>0)

            {

                x=x+(m%10)*(m%10);

                m=m/10;

            }

            if(p.get(x)!=null)

                return false;

            else

            {

                p.put(x,1);

                m=x;

            }

        }

        return true;        

    }

}

Leetcode#202Happy Number

标签：determine   positive   following   include   replace   

原文地址：http://7061299.blog.51cto.com/7051299/1640275