51Nod 1265 四点共面

题目链接

判断四点是否共面，判断四个点构成的三个向量混合积是否为0

#include<iostream>    #include<cstdio>    #include<math.h>    #include<cstring>    #include<algorithm>    #include<queue>    #include<set>    #include<vector>    using namespace std;    typedef struct node{double x,y,z;};int main(){      int n;cin>>n;for(int i=0;i<n;i++){node no[10];for(int j=0;j<4;j++){scanf("%lf%lf%lf",&no[j].x,&no[j].y,&no[j].z);}double x1=no[1].x-no[0].x,y1=no[1].y-no[0].y,z1=no[1].z-no[0].z;double x2=no[2].x-no[0].x,y2=no[2].y-no[0].y,z2=no[2].z-no[0].z;double x3=no[3].x-no[0].x,y3=no[3].y-no[0].y,z3=no[3].z-no[0].z;if(x1*(y2*z3-z2*y3)-y1*(x2*z3-z2*x3)+z1*(x2*y3-y2*x3)==0){printf("Yes\n");}else printf("No\n");}     return 0;  }