Acdream1197 points in cuboid

Question link: http://acdream.info/problem? PID = 1, 1197

Question: give some points. Each time a cube is given, the number of points in the cube is asked.

Idea: KD-tree.

const int N=111111;struct node{int x[3];int L,R;};node a[N];int root,n,m;void insert(int u,int k,int d){d%=3;if(a[k].x[d]<a[u].x[d]){if(a[u].L==-1) a[u].L=k;else insert(a[u].L,k,d+1);}else{if(a[u].R==-1) a[u].R=k;else insert(a[u].R,k,d+1);}}int p[3],q[3],ans;void cal(int u,int d){if(u==-1) return;int i;for(i=0;i<3;i++) if(a[u].x[i]<p[i]||a[u].x[i]>q[i]) break;if(i==3) ans++;d%=3;if(a[u].x[d]>=p[d]) cal(a[u].L,d+1);if(a[u].x[d]<=q[d]) cal(a[u].R,d+1);}void deal(){int i;for(i=1;i<=n;i++){a[i].L=a[i].R=-1;scanf("%d%d%d",&a[i].x[0],&a[i].x[1],&a[i].x[2]);if(i==1) root=i;else insert(root,i,0);}m=getInt();while(m--){for(i=0;i<3;i++) scanf("%d",&p[i]);for(i=0;i<3;i++) {scanf("%d",&q[i]);if(p[i]>q[i]) swap(p[i],q[i]);}ans=0;cal(root,0);printf("%d\n",ans);}}int main(){int num=0;while(scanf("%d",&n)!=-1){printf("Case #%d:\n",++num);deal();}}

 

Acdream1197 points in cuboid