Accept: 120    Submit: 289

Time Limit: 1000 mSec    Memory Limit : 32768 KB

 Problem Description

 Input

 Output

 Sample Input

 Sample Output

141994.02449787.965773.5031415.93

计算几何

#include <iostream>

#include <string.h>

#include <stdlib.h>

#include <algorithm>

#include <math.h>

#include <stdio.h>

using namespace std;

double l,r;

double ans;

double pi=2*asin(1.0);

int main()

{

    int t;

    scanf("%d",&t);

    while(t--)

    {

        scanf("%lf%lf",&l,&r);

        if(r>=l/sqrt(3.0))

            ans=pi*r*r;

        else if(r<=l/3.0)

            ans=sqrt(3.0)/3.0*l*l;

        else

        {

            double date=16*r*r-4.0/3.0*l*l;

            double x=(2*l-sqrt(date))/8;

            double s2=2*x*(l/sqrt(3.0))*1.0/2;

            double s3=pi*r*r*asin(x/r)/pi;

            double s4=s2-s3;

            ans=pi*r*r+s4*6;

        }

        printf("%.2f\n",ans);

    }

    return 0;

}