#KD-Tree,替罪羊树#洛谷 6224 [BJWC2014]数据

题目

平面上有 (N) 个点。需要实现以下三种操作:

  1. 在点集里添加一个点;

  2. 给出一个点,查询它到点集里所有点的曼哈顿距离的最小值;

  3. 给出一个点,查询它到点集里所有点的曼哈顿距离的最大值。


分析

用KD-Tree实现,维护区间横纵坐标最小值和最大值,
由于需要在点集中添加点,可能会导致K-D Tree树高不平衡,
那么直接用替罪羊树拍扁重建即可


代码

#include <cstdio>
#include <cctype>
#include <algorithm>
#include <queue>
#define rr register
using namespace std;
const int N=200011;
typedef long long lll;
const double alp=0.75;
int ran,root,n,m,ans;
inline signed iut(){
	rr int ans=0,f=1; rr char c=getchar();
	while (!isdigit(c)) c=getchar();
	while (isdigit(c)) ans=(ans<<3)+(ans<<1)+(c^48),c=getchar();
	return ans*f;
}
inline void print(int ans){
	if (ans>9) print(ans/10);
	putchar(ans%10+48);
}
inline signed min(int a,int b){return a<b?a:b;}
inline signed max(int a,int b){return a>b?a:b;}
struct rec{
	int p[2];
	bool operator <(const rec &t)const{
	    return p[ran]<t.p[ran];
	}
};
inline signed Abs(int x){return x<0?-x:x;}
struct KD_Tree{
	int mn[N][2],mx[N][2],son[N][2],siz[N],stac[N],TOP,tot; rec pt[N],p[N];
	inline void pup(int now){
		for (rr int i=0;i<2;++i){
			mn[now][i]=mx[now][i]=p[now].p[i];
			if (son[now][0]){
				mn[now][i]=min(mn[now][i],mn[son[now][0]][i]);
				mx[now][i]=max(mx[now][i],mx[son[now][0]][i]);
			}
			if (son[now][1]){
				mn[now][i]=min(mn[now][i],mn[son[now][1]][i]);
				mx[now][i]=max(mx[now][i],mx[son[now][1]][i]);
			}
		}
		siz[now]=siz[son[now][0]]+siz[son[now][1]]+1;
	}
	inline bool balance(int now){return alp*siz[now]>=(max(siz[son[now][0]],siz[son[now][1]]));}
	inline void recycle(int now){
		if (son[now][0]) recycle(son[now][0]);
		stac[++TOP]=now,pt[TOP]=p[now];
		if (son[now][1]) recycle(son[now][1]);
	}
	inline signed build(int l,int r,int Ran){
		if (l>r) return 0;
		rr int mid=(l+r)>>1,now=stac[mid];
		ran=Ran,nth_element(pt+l,pt+mid,pt+1+r),p[now]=pt[mid];
		son[now][0]=build(l,mid-1,Ran^1);
		son[now][1]=build(mid+1,r,Ran^1);
		pup(now);
		return now;
	}
	inline void rebuild(int &now,int Ran){
		TOP=0,recycle(now);
		now=build(1,TOP,Ran);
	}
	inline void Insert(int &now,rec W,int Ran){
		if (!now) now=++tot,p[now]=W;
		else{
			if (W.p[Ran]<=p[now].p[Ran]) Insert(son[now][0],W,Ran^1);
			    else Insert(son[now][1],W,Ran^1);
		}
		pup(now);
		if (!balance(now)) rebuild(now,Ran);
	}
	inline signed calcmn(int t,int x){
		rr int ans=0;
		for (rr int i=0;i<2;++i) ans+=max(mn[t][i]-p[x].p[i],0)+max(p[x].p[i]-mx[t][i],0);
		return ans;
	}
	inline signed calcmx(int t,int x){
		return max(Abs(p[x].p[0]-mn[t][0]),Abs(p[x].p[0]-mx[t][0]))+max(Abs(p[x].p[1]-mn[t][1]),Abs(p[x].p[1]-mx[t][1]));
	}
	inline void querymn(int now,int x){
		rr int t=Abs(p[x].p[0]-p[now].p[0])+Abs(p[x].p[1]-p[now].p[1]);
		if (ans>t) ans=t;
		rr int c0=calcmn(son[now][0],x),c1=calcmn(son[now][1],x);
		if (son[now][0]&&son[now][1]){
			if (c0<c1&&c0<ans){
				querymn(son[now][0],x);
				if (c1<ans) querymn(son[now][1],x);
			}else if (c1<ans){
				querymn(son[now][1],x);
				if (c0<ans) querymn(son[now][0],x);
			}
		}else if (son[now][0]){
			if (c0<ans) querymn(son[now][0],x);
		}else if (son[now][1]){
			if (c1<ans) querymn(son[now][1],x);
		}
	}
	inline void querymx(int now,int x){
		rr int t=Abs(p[x].p[0]-p[now].p[0])+Abs(p[x].p[1]-p[now].p[1]);
		if (ans<t) ans=t;
		rr int c0=calcmx(son[now][0],x),c1=calcmx(son[now][1],x);
		if (son[now][0]&&son[now][1]){
			if (c0>c1&&c0>ans){
				querymx(son[now][0],x);
				if (c1>ans) querymx(son[now][1],x);
			}else if (c1>ans){
				querymx(son[now][1],x);
				if (c0>ans) querymx(son[now][0],x);
			}
		}else if (son[now][0]){
			if (c0>ans) querymx(son[now][0],x);
		}else if (son[now][1]){
			if (c1>ans) querymx(son[now][1],x);
		}
	}
}Tre;
signed main(){
	n=iut();
	for (rr int i=1;i<=n;++i) Tre.Insert(root,(rec){iut(),iut()},0);
	for (rr int m=iut();m;--m){
		rr int opt=iut(),x,y;
		Tre.p[Tre.tot+1].p[0]=x=iut();
		Tre.p[Tre.tot+1].p[1]=y=iut();
		if (opt==0) Tre.Insert(root,(rec){x,y},0);
		    else if (opt==1) ans=0x3f3f3f3f,Tre.querymn(root,Tre.tot+1),print(ans),putchar(10);
		        else ans=-0x3f3f3f3f,Tre.querymx(root,Tre.tot+1),print(ans),putchar(10);
	}
	return 0;
}
原文地址:https://www.cnblogs.com/Spare-No-Effort/p/14912013.html