[51nod1265]四点共面

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 typedef long long ll;
 4 struct tpoint{
 5     double x,y,z;
 6     tpoint operator-(const tpoint &p)const{
 7         tpoint q;
 8         q.x=x-p.x;
 9         q.y=y-p.y;
10         q.z=z-p.z;
11         return q;
12     }
13 }p[4];
14 int delta(){
15     tpoint a,b,c;
16     a=p[0]-p[1];
17     b=p[0]-p[2];
18     c=p[0]-p[3];
19     return a.x*b.y*c.z+a.y*b.z*c.x+a.z*b.x*c.y-a.z*b.y*c.x-a.y*b.x*c.z-a.x*b.z*c.y;
20 }
21 int main(){
22     int t;
23     cin>>t;
24     while(t--){
25         for(int i=0;i<4;i++) cin>>p[i].x>>p[i].y>>p[i].z;
26             if(delta()==0) cout<<"Yes\n";
27             else cout<<"No\n";
28     }
29     return 0;
30 }