codeforce--600D - Area of Two Circles' Intersection

题意：求相交圆的面积。借鉴大神代码，精度超高。

 #include <fstream>
 #include <iostream>
 #include <string>
 #include <complex>
 #include <math.h>
 #include <set>
 #include <vector>
 #include <map>
 #include <queue>
 #include <stdio.h>
 #include <stack>
 #include <algorithm>
 #include <list>
 #include <ctime>
 #include <memory.h>
 #include <ctime>
 #include <assert.h>

 #define y1 aasdfasdfasdf

 #define eps 1e-16
 #define M_PI 3.141592653589793
 const int N = ;
 using namespace std;

 long double x1,y1,x2,y2,r1,r2;

 long double gd(long double x1,long double y1,long double x2,long double y2)
 {
     return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
 }

 long double solve_cos(long double a,long double b,long double c)
 {
     return acos((a*a+b*b-c*c)/(*a*b));
 }

 long double cut(long double ang,long double r)
 {
     long double s1,s2;
     s1=ang*r*r/;
     s2=sin(ang)*r*r/;
     return s1-s2;
 }

 long double solve()
 {
     if (r1<r2)
     {
         swap(x1,x2);
         swap(y1,y2);
         swap(r1,r2);
     }
     long double cd=gd(x1,y1,x2,y2);
     if (cd+r2<=r1+eps)
         return r2*r2*M_PI;
     if (cd>=r1+r2-eps)
         return ;
     long double ang1=solve_cos(cd,r1,r2);
     long double ang2=solve_cos(cd,r2,r1);
     return cut(ang1*,r1)+cut(ang2*,r2);
 }

 int main()
 {
     cin>>x1>>y1>>r1;
     cin>>x2>>y2>>r2;
     cout.precision();
     cout<<fixed<<solve()<<endl;
     return ;
 }