poj2546 计算几何 Circular Area 求两圆相交面积

这道题wa了一晚上 原因是

1.没看到多组样例，本人写的时候也从来没有习惯写多组样例

2.double类型只能用%lf读，用%f写啊！我两个都用了%lf。。。。。。。。。。。。。。话说写的时候还有点犹豫。。。。。。

 

不说了 我是个傻孩子orz

 

Circular Area

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 6455		Accepted: 2432

Description

Your task is to write a program, which, given two circles, calculates the area of their intersection with the accuracy of three digits after decimal point.

Input

In the single line of input file there are space-separated real numbers x1 y1 r1 x2 y2 r2. They represent center coordinates and radii of two circles.

Output

The output file must contain single real number - the area.

Sample Input

20.0 30.0 15.0 40.0 30.0 30.0

Sample Output

608.366


上代码

#include<iostream>
#include<cmath>
#include<cstdio>

using namespace std;

double x1,yy,r1,x2,y2,r2;
double l;
double pi = acos(-1);

double dis(){
    double m = (x1-x2)*(x1-x2) + (yy-y2)*(yy-y2);
    return sqrt(m);
}

int main(){
//    cout << pi <<endl;
    while(scanf("%lf%lf%lf%lf%lf%lf",&x1,&yy,&r1,&x2,&y2,&r2) != EOF){
        l = dis();
        
        if(l >= r1 + r2){
            printf("0.000\n");
        }
        else{
            int minr = r1;
            if(r1 > r2) minr = r2;
            int maxr = r1 + r2 - minr;
            if(maxr - l >= minr){
                printf("%.3lf\n",pi*minr*minr);
            }
            else{
                double alpha1,alpha2,s,s1,s2;
                alpha1 = acos((r1*r1 + l*l - r2*r2)/(2*r1*l));
                alpha2 = acos((r2*r2 + l*l - r1*r1)/(2*r2*l));
                s1 = alpha1*r1*r1;
                s2 = alpha2*r2*r2;
                s = s1 + s2 - l*r1*sin(alpha1);
                printf("%.3lf\n",s);
            }
        }
    }
    return 0;
}