hdu 4355 简单三分找最小值

#include<stdio.h>
#include<string.h>
#include<iostream>
#include<math.h>
using namespace std;
#define exp 1e-6

int n;
double pos[50010],weight[50010];
double min(double a,double b)
{
return a<b?a:b;
}
double query(double x)
{
int i;
double sum=0;
for(i=1;i<=n;i++)
{
double k=pos[i]-x;
if(k<0) k=-k;
sum+=k*k*k*weight[i];
}
return sum;
}
int main()
{
int T,i,j,d=1;
scanf("%d",&T);
while(T--)
{
scanf("%d",&n);
for(i=1;i<=n;i++)
{
scanf("%lf%lf",&pos[i],&weight[i]);
}
double left=pos[1];
double right=pos[n];
while(right-left>exp)
{
double mid=(2*left+right)/3;
double mmid=(left+2*right)/3;
if(query(mid)>query(mmid))
{
left=mid;
}
else right=mmid;
}
printf("Case #%d: %.0lf\n",d++,query(left));
}
return 0;
}