HUD 1411--校庆神秘建筑(欧拉四面体体积计算)

#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstdio>
using namespace std;
//p,q,r为AD,BD,CD;n,l,m为AB,BC,AC;
double V_tetrahedron(double l, double m, double n, double q, double p, double r) {
    //return sqrt((4 * p*p*q*q*r*r - p*p*(q*q + r*r - l*l)*(q*q + r*r - l*l) - q*q*(r*r + p*p - m*m)*(r*r + p*p - m*m) - r*r*(p*p + q*q - n*n)*(p*p + q*q - n*n) + (p*p + q*q - n*n)*(q*q + r*r - l*l)*(r*r + p*p - m*m))) / 12.0;
    double x = q*q + r*r - l*l, y = r*r + p*p - m*m, z = p*p + q*q - n*n;
    return sqrt((4 * p*p*q*q*r*r - p*p*x*x - q*q*y*y - r*r*z*z + z*x*y)) / 12.0;
}
int main(){
    double l,m,n,q,p,r;
    while(cin>>n>>m>>p>>l>>q>>r){
    double ans=V_tetrahedron(l,m,n,q,p,r);
    printf("%.4lf\n",ans);
    }
    return 0;
}