hdu 3714

#include <cstdio>  #include <algorithm>#include <iostream>using namespace std;    const int maxn = 10000 + 10;  int n, a[maxn], b[maxn], c[maxn];    double F(double x)  {      double ans = a[0]*x*x + b[0]*x + c[0];      for(int i=1; i<n; ++i)          ans = max(ans, a[i]*x*x + b[i]*x +c[i]);      return ans;  }    int main()  {  #ifdef test       freopen("c://test.txt","r",stdin);   #endif       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]);          double L = 0.0, R = 1000.0;          for(i = 0; i < 100; ++i)          {              double m1 = L + (R - L)/3;              double m2 = R - (R - L)/3;              if(F(m1) < F(m2) ) R = m2;              else L = m1;          }          printf("%.4lf\n", F(L));      }      return 0;  }