笔记

#include <iostream>
using namespace std;

int main()
{
    int n; cin >> n;
    while (n --)
    {
        int x, sum = 0; cin >> x;
        // 使用约数的优化写法，不需要枚举所有
        for (int i = 1; i * i <= x; i ++)
        {
            if (x % i == 0) 
            {
                if (i < x) sum += i;
                if (i != x / i && x / i < x) sum += x / i;
            }
        }
        if (sum == x) cout << x << " is perfect" << endl;
        else cout << x << " is not perfect" << endl;
    }

    return 0;
}