Lightoj 1118 incredible molecules Circle area intersection, template

See Kuangbin God's version of the son, their own are afraid to put on the ...

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cstdlib>
#include <iostream>
#include <vector>
#include <cmath>
#include <queue>
#include <map>
#include <string>
#include <stack>

using namespace Std;
Const double Pi=acos (-1.0);
const double EPS=1E-10;
Double Add (double a,double b)//floating-point addition with error
{
if (ABS (A + B) < EPS * (ABS (a) + ABS (b))) return 0;
return a + B;
}
struct POINT
{
Double x, y;
Point (double tx = 0,double ty = 0): X (TX), y (ty) {}
Point operator + (point P)
{
Return point (Add (x,p.x), add (Y,P.Y));
}
Point operator-(point P)
{
Return point (Add (x,-p.x), add (Y,-P.Y));
}
Point operator * (double D)
{
return Point (x * d,y * d);
}
Point operator/(double D)
{
Return point (X/D,Y/D);
}
Point Move (double a,double D)//starting from X positive direction, counterclockwise
{
return point (x + d * cos (a), y + d * sin (a));
}
void Read ()
{
scanf ("%lf%lf", &x,&y);
}
};

struct Circle
{
Point O;
Double R;
Circle (Double tx = 0,double Ty = 0,double tr = 0): O (tx,ty), R (TR) {}
void Read ()
{
O.read ();
scanf ("%lf", &r);
}
void Out ()
{
printf ("%.8f%.8f%.8f\n", o.x,o.y,r);
}
Double Area ()
{
return R*R*PI;
}
};
Double X_mult (Point sp, Dot EP, point op)//cross product
{
Return (sp.x-op.x) * (EP.Y-OP.Y)-(SP.Y-OP.Y) * (ep.x-op.x);
}
Double Cross (Point a,point b,point C)//dot Product
{
Return (a.x-c.x) * (b.x-c.x) + (A.Y-C.Y) * (B.Y-C.Y);
}
Double Dist (point A,point B)
{
return sqrt ((a.x-b.x) * (a.x-b.x) + (A.Y-B.Y) * (A.Y-B.Y));
}
Double Solve (Circle c1,circle C2)
{
Double D=dist (C1.O,C2.O);
if (c1.r+c2.r<d+eps) return 0;
if (D<fabs (C1.R-C2.R) +eps)
{
Double R=min (C1.R,C2.R);
return pi*r*r;
}
Double x= (D*D+C1.R*C1.R-C2.R*C2.R)/(2*D);
Double T1=acos (X/C1.R);
Double T2=acos ((d-x)/C2.R);
return C1.r*c1.r*t1+c2.r*c2.r*t2-d*c1.r*sin (T1);
}
int main ()
{
int T,ncas=1;
scanf ("%d", &t);
while (t--)
{
Circle c1,c2;
C1. Read ();
C2. Read ();
printf ("Case%d:%.10f\n", Ncas++,solve (C1,C2));
}
return 0;
}

Lightoj 1118 incredible molecules Circle area intersection, template