Benelux Algorithm Programming Contest 2014 Final G： Growling Gears

G： Growling Gears：

The Best Acceleration Production Company specializes in multi-gear engines. The performance of an engine in a certain gear, measured in the amount of torque produced, is not constant: the amount of torque depends on the RPM of the engine. This relationship can be described using a torque-RPM curve.

For the latest line of engines, the torque-RPM curve of all gears in the engine is a parabola of the form T = -aR^2 +bR+cT=−aR2+bR+c,where $R$ is the RPM of the engine,and $T$ is the resulting torque.

Given the parabolas describing all gears in an engine, determine the gear in which the highest torque is produced. The first gear is gear $1$, the second gear is gear $2$, etc. There will be only one gear that produces the highest torque: all test cases are such that the maximum torque is at least $1$ higher than the maximum torque in all the other gears.

Input Format

On the first line one positive number: the number of test cases, at most $100$. After that per test case:

• one line with a single integer $n$ $(1\le n\le 10)$: the number of gears in the engine.
• $n$ lines, each with three space-separated integers $a$, $b$ and $c$ (1 \le a, b, c \le 10^4)(1≤a,b,c≤104): the parameters of the parabola T = -aR^2 +bR+cT=−aR2+bR+c describing the torque-RPM curve of each engine.

Output Format

Per test case:

• one line with a single integer: the gear in which the maximum torque is generated.

样例输入

3
1
1 4 2
2
3 126 1400
2 152 208
2
3 127 1400
2 154 208

样例输出

1
2
2

题目来源

Benelux Algorithm Programming Contest 2014 Final

代码：

#include <iostream>
using namespace std;
int main(int argc, char const *argv[]){	
	int t;
	cin >> t;
	while(t--){
		int n;
		cin >> n;
		int max = 0;
		int ans = 0;
		int flag = 0;
		while(n --){
			int a, b, c;
			cin >> a >> b >> c;
			flag ++;
			if(max < double(b * b ) / (4*a) + c){
				max =  double(b * b ) / (4*a) + c;
				ans = flag;
			}

		}
		cout << ans << endl;
	}
	return 0;
}