【BZOJ1941】【SDOI2010】Hide and Seek、KDTree【数组版】 模板、

直接贴代码。

推荐一篇KDT讲解、http://blog.csdn.net/wyfcyx_forever/article/details/40182345

#include <cmath>#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>#define N 501000#define inf 0x3f3f3f3f#define d(x,y) (((x)>(y))?((x)-(y)):((y)-(x)))using namespace std;int n,ans=inf;int judge;struct Point{int x,y;Point(int _x=0,int _y=0):x(_x),y(_y){}bool operator < (const Point &a)const{return judge?y<a.y:x<a.x;}}P[N];inline int dis(Point &a,Point &b){return d(a.x,b.x)+d(a.y,b.y);}struct KDT{int son[N][2],cnt;int x[N][2],y[N][2];void init(int a,Point &p){x[a][0]=x[a][1]=p.x;y[a][0]=y[a][1]=p.y;}void update(int f){int s;if(son[f][0]){s=son[f][0];x[f][0]=min(x[f][0],x[s][0]);y[f][0]=min(y[f][0],y[s][0]);x[f][1]=max(x[f][1],x[s][1]);y[f][1]=max(y[f][1],y[s][1]);}if(son[f][1]){s=son[f][1];x[f][0]=min(x[f][0],x[s][0]);y[f][0]=min(y[f][0],y[s][0]);x[f][1]=max(x[f][1],x[s][1]);y[f][1]=max(y[f][1],y[s][1]);}}int maxdis(int a,Point &p){int ret=0;ret+=max(d(x[a][0],p.x),d(x[a][1],p.x));ret+=max(d(y[a][0],p.y),d(y[a][1],p.y));return ret;}int mindis(int a,Point &p){int ret=0;if(p.x<x[a][0])ret+=x[a][0]-p.x;else if(x[a][1]<p.x)ret+=p.x-x[a][1];if(p.y<y[a][0])ret+=y[a][0]-p.y;else if(y[a][1]<p.y)ret+=p.y-y[a][1];return ret;}int newnode(Point &p){init(++cnt,p);return cnt;}int build(int l,int r,int jd=0){int mid=l+r>>1,t=0;judge=jd;nth_element(P+l,P+mid,P+r+1);if(l<mid)t=build(l,mid-1,!jd);int q=newnode(P[mid]);son[q][0]=t;if(mid<r)son[q][1]=build(mid+1,r,!jd);update(q);return q;}int Maxdis,Mindis;void querymin(int f,Point &p){int Dis[3];Dis[2]=dis(P[f],p);if(Dis[2])Mindis=min(Mindis,Dis[2]);Dis[0]=Dis[1]=inf;if(son[f][0])Dis[0]=mindis(son[f][0],p);if(son[f][1])Dis[1]=mindis(son[f][1],p);int t=Dis[0]>Dis[1];if(son[f][t]&&Dis[t]<Mindis)querymin(son[f][t],p);t^=1;if(son[f][t]&&Dis[t]<Mindis)querymin(son[f][t],p);}void querymax(int f,Point &p){int Dis[3];Dis[2]=dis(P[f],p);if(Dis[2])Maxdis=max(Maxdis,Dis[2]);Dis[0]=Dis[1]=0;if(son[f][0])Dis[0]=maxdis(son[f][0],p);if(son[f][1])Dis[1]=maxdis(son[f][1],p);for(int i=2,t=Dis[0]<Dis[1];i--;t^=1)if(son[f][t]&&Dis[t]>Maxdis)querymax(son[f][t],p);}int query(int root,int q){Mindis=inf,Maxdis=0;querymax(root,P[q]),querymin(root,P[q]);//printf("(%d,%d) : %d %d\n",P[q].x,P[q].y,Mindis,Maxdis);return Maxdis-Mindis;}}kdt;int main(){//freopen("test.in","r",stdin);scanf("%d",&n);for(int i=1;i<=n;i++)scanf("%d%d",&P[i].x,&P[i].y);int root=kdt.build(1,n);for(int i=1;i<=n;i++)ans=min(ans,kdt.query(root,i));printf("%d\n",ans);return 0;}