为什么如下代码在洛谷只能拿20'？

#include <bits/stdc++.h>

#define endl '\n'

using namespace std;

int T, M;
int a, b, c, delta;

signed main() {
//	freopen("uqe.in", "r", stdin);
//	freopen("uqe.out", "w", stdout);
	ios::sync_with_stdio(false);
	cin.tie(0); cout.tie(0);
	cin >> T >> M;
	for(int i = 1; i <= T; i ++) {
		cin >> a >> b >> c;
		delta = b * b - 4 * a * c;
		if(delta < 0) {
			cout << "NO" << endl;
		} else {
			cout << max((-b+sqrt(delta))/(2*a), (-b-sqrt(delta))/(2*a)) << endl;
		}
	}
	return 0;
}