LA 5009 - Error Curves(三分)

/*

*/
#include<bits/stdc++.h>
using namespace std;

const int N = 1e4+5;
int n,a
,b
,c
;
double f(double x)
{
double maxn = a[0]*x*x+b[0]*x+c[0];
for(int i = 1;i < n;i++)
maxn = max(maxn,a[i]*x*x+b[i]*x+c[i]);
return maxn;
}
int main()
{
int T;
scanf("%d",&T);
while(T--)
{
scanf("%d",&n);
for(int i = 0;i < n;i++)
scanf("%d%d%d",&a[i],&b[i],&c[i]);
int cnt = 0;
double l = 0,r = 1000,m1,m2;
while(cnt++ < 100)
{
m1 = l+(r-l)/3;
m2 = r-(r-l)/3;
if(f(m1) < f(m2))
r = m2;
else
l = m1;
}
printf("%.4f\n",f(m1));
}
return 0;
}