leetCode(29):Happy Number

Posted 2020-09-14 yjbjingcha

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

class Solution {
public:
    bool isHappy(int n) {
        map<int,int> value;	
    	while(n!=1)
    	{
    		value[n]=1;
    		int remain;
    		int tmp=0;
    		while(n!=0)
    		{
    			remain=n%10;
    			tmp+=remain*remain;
    			n=n/10;
    		}
    		n=tmp;
    		if(value.find(n)!=value.end())
    			break;//是否已经出现过
    	}
    	if(n!=1)
    		return false;
    	return true;
        
    }
};