二、阅读程序-1

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#include <iostream>
#include <cmath>
using namespace std;

const double r = acos(0.5);

int a1, b1, c1, d1;
int a2, b2, c2, d2;

inline int sq(const int x) { return x * x; }
//inline的作用是减少函数的开销
inline int cu(const int x) { return x * x * x; } 
int main()
{
    cout.flags(ios::fixed);
    cout.precision(4); 
    cin >> a1 >> b1 >> c1 >> d1;
    cin >> a2 >> b2 >> c2 >> d2; 
   int t = sq(a1 - a2) + sq(b1 - b2) + sq(c1 - c2);

   if (t <= sq(d2 - d1)) cout << cu(min(d1, d2)) * r * 4;
    else if (t >= sq(d2 + d1)) cout << 0;
         else {
             double x = d1 - (sq(d1) - sq(d2) + t) /sqrt(t)/2;
             double y = d2 - (sq(d2) - sq(d1) + t) / sqrt(t)/2;
             cout << (x * x * (3 * d1 - x) + y * y * (3 * d2 - y)) * r;
        }
    cout << endl;
    return 0;
}