hdu 4347 kdtree kdtree+优先队列

The course of Software Design and Development Practice is objectionable. ZLC is facing a serious problem .There are many points in K-dimensional space .Given a point. ZLC need to find out the closest m points. Euclidean distance is used as the distance metric between two points. The Euclidean distance between points p and q is the length of the line segment connecting them.In Cartesian coordinates, if p = (p ₁, p ₂,..., p _n) and q = (q ₁, q ₂,..., q _n) are two points in Euclidean n-space, then the distance from p to q, or from q to p is given by: 

Can you help him solve this problem?

Input

In the first line of the text file .there are two non-negative integers n and K. They denote respectively: the number of points, 1 <= n <= 50000, and the number of Dimensions,1 <= K <= 5. In each of the following n lines there is written k integers, representing the coordinates of a point. This followed by a line with one positive integer t, representing the number of queries,1 <= t <=10000.each query contains two lines. The k integers in the first line represent the given point. In the second line, there is one integer m, the number of closest points you should find,1 <= m <=10. The absolute value of all the coordinates will not be more than 10000. 
There are multiple test cases. Process to end of file.

Output

For each query, output m+1 lines: 
The first line saying :”the closest m points are:” where m is the number of the points. 
The following m lines representing m points ,in accordance with the order from near to far 
It is guaranteed that the answer can only be formed in one ways. The distances from the given point to all the nearest m+1 points are different. That means input like this: 
2 2 
1 1 
3 3 
1 
2 2 
1 
will not exist.

Sample Input

3 21 11 33 422 322 31

M维kdtree

#include <bits/stdc++.h>using namespace std;typedef long long ll;const int MAXN = 5e4+10;const ll inf=(1ll<<60);int n,m;int nowD;int root;int ql[5];int k;typedef long long ll;struct Node{int id;ll dis;Node(){}Node(int _id,ll _dis):id(_id),dis(_dis){}bool operator < (const Node &rhs) const{return dis<rhs.dis;}};struct node{int Min[5],Max[5];int d[5];int l,r;}t[MAXN];priority_queue<Node> Q;inline int getint(){int w=0,q=0;char c=getchar();while((c<'0'||c>'9')&&c!='-') c=getchar();if(c=='-') q=1,c=getchar();while(c>='0'&&c<='9') w=w*10+c-'0',c=getchar();return q?-w:w;}inline ll dist(int p){ll dis=0;for(int i=0;i<m;i++){if(ql[i]<t[p].Min[i]) dis+=1ll*(t[p].Min[i]-ql[i])*(t[p].Min[i]-ql[i]);if(ql[i]>t[p].Max[i]) dis+=1ll*(ql[i]-t[p].Max[i])*(ql[i]-t[p].Max[i]);}return dis;}inline bool cmp(node q,node qq){if(q.d[nowD]==qq.d[nowD]){for(int i=0;i<m;i++){if(i==nowD) continue;if(q.d[i]==qq.d[i]) continue;return q.d[i]<qq.d[i];}}return q.d[nowD]<qq.d[nowD];}inline void kd_updata(int now){if(t[now].l){for(int i=0;i<m;i++){if(t[t[now].l].Max[i]>t[now].Max[i]) t[now].Max[i]=t[t[now].l].Max[i];if(t[t[now].l].Min[i]<t[now].Min[i])t[now].Min[i]=t[t[now].l].Min[i];}}if(t[now].r){for(int i=0;i<m;i++){if(t[t[now].r].Max[i]>t[now].Max[i]) t[now].Max[i]=t[t[now].r].Max[i];if(t[t[now].r].Min[i]<t[now].Min[i])t[now].Min[i]=t[t[now].r].Min[i];}}}inline int kd_build(int l,int r,int D){int mid=(l+r)/2;nowD=D;nth_element(t+l+1,t+mid+1,t+r+1,cmp);if(l!=mid) t[mid].l=kd_build(l,mid-1,(D+1)%m);if(r!=mid) t[mid].r=kd_build(mid+1,r,(D+1)%m);for(int i=0;i<m;i++)t[mid].Max[i]=t[mid].Min[i]=t[mid].d[i];kd_updata(mid);return mid;}inline void kd_query(int p){ll dl,dr,d0=0;for(int i=0;i<m;i++)d0+=(1ll*t[p].d[i]-ql[i])*(t[p].d[i]-ql[i]);if(Q.size()<k)Q.push(Node(p,d0));else {if(Q.size()==k&&Q.top().dis>d0){Q.pop();Q.push(Node(p,d0));}}if(t[p].l) dl=dist(t[p].l);else dl=inf;if(t[p].r) dr=dist(t[p].r);else dr=inf;if(dl<dr){if(Q.size()<k||dl<Q.top().dis) kd_query(t[p].l);if(Q.size()<k||dr<Q.top().dis) kd_query(t[p].r);}else{if(Q.size()<k||dr<Q.top().dis) kd_query(t[p].r);if(Q.size()<k||dl<Q.top().dis) kd_query(t[p].l);}}void dfs(int x){if(x==k+1)return ;Node f=Q.top();Q.pop();dfs(x+1);printf("%d",t[f.id].d[0] );for(int i=1;i<m;i++)printf(" %d",t[f.id].d[i] );printf("\n");}int main(){    while(~scanf("%d%d",&n,&m))    {    memset(t,0,sizeof(t));        for(int i=1;i<=n;i++)            for(int j=0;j<m;j++)            t[i].d[j]=getint();        root=kd_build(1,n,0);        int q;        scanf("%d",&q);        while(q--){        for(int i=0;i<m;i++)        ql[i]=getint();        k=getint();        while(!Q.empty()) Q.pop();        kd_query(root);        printf("the closest %d points are:\n",k );        dfs(1);        }    }}

Sample Output