题解 | #完全数计算#

#include <iostream>
using namespace std;

bool IsPerfectNum(int num)
{
    int a;
    int result = 1;
    for(a = 2; a<= num/a - 1; a++)
    {
        if(num%a == 0)
        {
            result += a;
            result += num/a;
        }
    }
    if(result == num)
    {
        //cout<<num;
        return true;
    }
    return false;
}

int main()
{
    int input;
    while(cin>>input)
    {
        int num = 0;
        for(int i = 2; i <= input; i++)
        {
            if(IsPerfectNum(i))
            {
                num++;
            }
        }
        cout << num <<endl;
    }
    return 0;
}