HDU5432-Pyramid Split

#include<stdio.h>
#include<string.h>
#include<math.h>
#define eps 1e-5
double a[10005],b[10005];
int n;
int bSearch(double begin,double end,double e)
{
    double mid, left = begin, right = end;
    while(right-left>eps)
    {
        mid = (left + right)/2;
        double sum=0;
        for(int i=0;i<n;i++){
            if(a[i]<mid) continue;
            double r=(a[i]-mid)/a[i]*b[i];
            double h=a[i]-mid;
            sum+=1.0/3*r*r*h;
        }
        if(fabs(sum-e)<eps) return mid;
        if(sum-e>eps) left = mid;
        else right = mid ;
    }
    return left;
}
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {

        scanf("%d",&n);
        for(int i=0;i<n;i++)
            scanf("%lf",&a[i]);
        for(int i=0;i<n;i++)
            scanf("%lf",&b[i]);
        double sum=0;
        for(int i=0;i<n;i++){
            sum+=1.0/3*b[i]*b[i]*a[i];
        }
        sum/=2;
        double k=bSearch(0,5000,sum);
        printf("%d\n",(int)k);
    }
    return 0;
}