using namespace std;
#include <iostream>
#include <iomanip>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <complex>

//这道题pi后面加多少位都没关系
double pi = 3.141592653589793238462643383279502884197;

typedef complex<double> CX;
double circle_inter(CX o1, double r1, CX o2, double r2){
	double d = sqrt( norm(o1-o2) );
	if( d >= r1 + r2 ) return 0;
	if( d <= abs(r1 - r2) ) return min(pi * r1 * r1, pi * r2 * r2 );
	double t1 = acos(( d*d + r1*r1 - r2*r2 ) / 2 / d / r1);
	double t2 = acos(( d*d + r2*r2 - r1*r1 ) / 2 / d / r2);
	double area = pi * r1 * r1 + pi * r2 * r2;
	area -= t1 * r1 * r1;
	area -= t2 * r2 * r2;
	double s = ( r1 + r2 + d )/2;
	area += sqrt( s * (s - r1 ) * (s - r2 ) * (s - d)) * 2;
	return pi*r1*r1 + pi*r2*r2 - area;
}

int main() {
	double x1, y1, x2, y2, r1, r2;
	while(cin >> x1 >> y1 >> r1 >> x2 >> y2 >> r2){
		double area = circle_inter( CX(x1,y1), r1, CX(x2, y2), r2);

// 使用这句就会WA
//	   	printf("%.3lf\n", circle_inter( CX(x1,y1), r1, CX(x2, y2), r2));

// 这句就AC了
		cout<<setiosflags(ios::fixed)<<setprecision(3)<<area<<endl;
	}
	return 0;
}

• Re:这道题千万不要用printf，用了就WA，有哪位大牛解释一下为啥... (7) ceshi0001 2010-01-25 18:04:29
• Re:这道题千万不要用printf，用了就WA，有哪位大牛解释一下为啥... (1221) 0912070002 2010-06-13 01:56:38
• Re:这道题千万不要用printf，用了就WA，有哪位大牛解释一下为啥... (34) YanXB 2015-05-17 19:08:13