三分求助

int t, n;
const double eps = 0.000000001l;
struct node {
	double a, b, c;
}mp[10001];
double gett(double x) {
	double ans = 0;
	for (int i = 1; i <= n; i++) {
		ans = max(ans, mp[i].a * x * x + mp[i].b * x + mp[i].c);
	}
	return ans;
}
signed main() {
	t = read();
	while (t--) {
		n = read();
		for (int i = 1; i <= n; i++) {
			mp[i].a = read(), mp[i].b = read(), mp[i].c = read();
		}
		double l = 0, r = 1000;
		while (r - l > eps) {
			double lmid = (r - l) / 3.0 + l, rmid = r - (r - l) / 3.0;
			double lg = gett(lmid), rg = gett(rmid);
			if (lg >= rg)l = lmid;
			else r = rmid;
		}printf("%.4lf\n", gett(l));
	}
	return 0;
}