leetcode--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

解题思路：

#include <iostream>
#include <algorithm>
#include <math.h>
using namespace std;



int sum(int n)
{
    int sum=0;
    while(n)
    {
        sum+=pow(n%10,2);
        n /= 10;
    }
    return sum;
}


bool isHappy(int n)
{
    int m=6;
    while(m--)
    {
        n=sum(n);
        if(n==1)
            return true;
    }
    return false;
}



int main()
{
    int n=3;
    if(isHappy(n)) cout<<"true"<<endl;
    else cout<<"false"<<endl;
    return 0;
}