51nod 1265 四点共面

#include <bits/stdc++.h>using namespace std;struct node{long long x,y,z;node(){};node(int a,int b,int c){x=a;y=b;z=c;};};long long dotmulti(node n1,node n2){return n1.x*n2.x+n1.y*n2.y+n1.z*n2.z;}node chamulti(node n1,node n2){node ret;ret.x=n1.y*n2.z-n1.z*n2.y;ret.y=-n1.x*n2.z+n1.z*n2.x;ret.z=n1.x*n2.y-n1.y*n2.x;return ret;}int main(){long long t,x[5],y[5],z[5],i;cin>>t;while(t--){for(i=0;i<4;i++)scanf("%lld%lld%lld",&x[i],&y[i],&z[i]);if(dotmulti(node(x[3]-x[0],y[3]-y[0],z[3]-z[0]),chamulti(node(x[1]-x[0],y[1]-y[0],z[1]-z[0]),node(x[2]-x[0],y[2]-y[0],z[2]-z[0])))==0)printf("Yes\n");elseprintf("No\n");}}