hdu 5120 圆相交面积+组合数学

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http://acm.hdu.edu.cn/showproblem.php?pid=5120
圆环的交 = 大圆交-2个大小圆交+小圆交
最讨厌这些模板题！干.
<span style="font-size:14px;">#include <cstdio>#include <cstdlib>#include <cmath>#include <cstring>#include <string>#include <queue>#include <map>#include <iostream>#include <sstream>#include <algorithm>using namespace std;#define RD(x) scanf("%d",&x)#define RD2(x,y) scanf("%d%d",&x,&y)#define RD3(x,y,z) scanf("%d%d%d",&x,&y,&z)#define clr0(x) memset(x,0,sizeof(x))#define clr1(x) memset(x,-1,sizeof(x))#define eps 1e-9const double pi = acos(-1.0);typedef long long LL;const int inf = 1000000000;const int maxn = 1e6+5;const double Pi=acos(-1.0);double Rad2Deg(double rad){    return (rad*180.0/Pi);}double Deg2Rad(double deg){    return (deg*Pi/180.0);}double ArcCos(double val){    return Rad2Deg(acos(val));}double Sin(double deg){    return sin(Deg2Rad(deg));}struct CIRCLE{    double x;    double y;    double r;    CIRCLE(){}    CIRCLE(double xx,double yy,double rr){        x=xx; y=yy; r=rr;    }};struct POINT{    double x;    double y;    POINT():x(0),y(0){};    POINT(double xx,double yy):x(xx),y(yy){    }};double Distance(const POINT& a,const POINT& b){    return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));}POINT Center(const CIRCLE& circle){    return POINT(circle.x,circle.y);}double Area(const CIRCLE& circle){    return Pi*circle.r*circle.r;}double CommonArea(const CIRCLE& A,const CIRCLE &B){    double area=0.0;    const CIRCLE& M=(A.r>B.r)?A:B;    const CIRCLE& N=(A.r>B.r)?B:A;    double D=Distance(Center(M),Center(N));    if((D<M.r+N.r)&&(D>M.r-N.r)){        double cosM=(M.r*M.r+D*D-N.r*N.r)/(2.0*M.r*D);        double cosN=(N.r*N.r+D*D-M.r*M.r)/(2.0*N.r*D);        double alpha=2.0*ArcCos(cosM);        double beta=2.0*ArcCos(cosN);        double TM=0.5*M.r*M.r*Sin(alpha);        double TN=0.5*N.r*N.r*Sin(beta);        double FM=(alpha/360.0)*Area(M);        double FN=(beta/360.0)*Area(N);        area=FM+FN-TM-TN;    }else if(D<=M.r-N.r){        area=Area(N);    }    return area;}double work(){    double r,R;        double x1,y1;        double x2,y2;        //cin>>r>>R>>x1>>y1>>x2>>y2;        scanf("%lf%lf%lf%lf%lf%lf",&r,&R,&x1,&y1,&x2,&y2);        CIRCLE cr1(x1,y1,r);        CIRCLE cr2(x2,y2,r);        CIRCLE cR1(x1,y1,R);        CIRCLE cR2(x2,y2,R);        double ans=CommonArea(cR1,cR2)+CommonArea(cr1,cr2);        ans-=CommonArea(cr1,cR2);        ans-=CommonArea(cR1,cr2);    return ans;}int main(){    int _,cas = 1;    RD(_);    while(_--){        printf("Case #%d: %.6lf\n",cas++,work());    }    return 0;}/**/</span>
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