BZOJ 1941 Sdoi2010 Hide and Seek K-Dimensional-Tree

题目大意：给定平面上的n个点，定义距离为曼哈顿距离，求一个点到其他所有点的最大距离与最小距离之差最小

KDTree……这东西好神啊

注意计算最小距离的时候不能把自己也算进去= =

#include 
#include 
#include 
#include 
#define M 500500
#define INF 0x3f3f3f3f
using namespace std;
struct Point{
	int x,y;
	Point() {}
	Point(int _,int __):
		x(_),y(__) {}
	friend istream& operator >> (istream &_,Point &p)
	{
		scanf("%d%d",&p.x,&p.y);
		return _;
	}
	friend bool operator != (const Point &p1,const Point &p2)
	{
		return p1.x!=p2.x || p1.y!=p2.y ;
	}
	friend int Distance(const Point &p1,const Point &p2)
	{
		return abs(p1.x-p2.x) + abs(p1.y-p2.y);
	}
}points[M];
int n,ans=INF;
bool Compare_x(const Point &p1,const Point &p2)
{
	return p1.x < p2.x;
}
bool Compare_y(const Point &p1,const Point &p2)
{
	return p1.y < p2.y;
}
namespace K_Dimension_Tree{
	struct abcd{
		abcd *ls,*rs;
		Point p;
		int x1,y1,x2,y2;
		abcd() {}
		abcd(const Point &_):p(_)
		{
			x1=x2=p.x;
			y1=y2=p.y;
		}
		void Push_Up(abcd *x)
		{
			x1=min(x->x1,x1);
			x2=max(x->x2,x2);
			y1=min(x->y1,y1);
			y2=max(x->y2,y2);
		}
		int Min_Distance(const Point &p)
		{
			int re=0;
			if(p.xx2) re+=p.x-x2;
			if(p.yy2) re+=p.y-y2;
			return re;
		}
		int Max_Distance(const Point &p)
		{
			int re=0;
			re+=max(p.x-x1,x2-p.x);
			re+=max(p.y-y1,y2-p.y);
			return re;
		}
	}mempool[M],*C=mempool,*root;
	void Build_Tree(abcd *&x,int l,int r,bool flag)
	{
		if(l>r)
		{
			x=0x0;
			return ;
		}
		int mid=l+r>>1;
		nth_element(points+l,points+mid,points+r+1,flag?Compare_y:Compare_x);
		x=new (C++)abcd(points[mid]);
		Build_Tree(x->ls,l,mid-1,flag^1);
		Build_Tree(x->rs,mid+1,r,flag^1);
		if(x->ls) x->Push_Up(x->ls);
		if(x->rs) x->Push_Up(x->rs);
	}
	void Get_Min(abcd *x,const Point &p,int &ans)
	{
		if(x->p!=p)
			ans=min(ans,Distance(x->p,p));
		int l_dis=x->ls?x->ls->Min_Distance(p):INF;
		int r_dis=x->rs?x->rs->Min_Distance(p):INF;
		if( l_dis < r_dis )
		{
			if( x->ls && l_disls,p,ans);
			if( x->rs && r_disrs,p,ans);
		}
		else
		{
			if( x->rs && r_disrs,p,ans);
			if( x->ls && l_disls,p,ans);
		}
	}
	void Get_Max(abcd *x,const Point &p,int &ans)
	{
		ans=max(ans,Distance(x->p,p));
		int l_dis=x->ls?x->ls->Max_Distance(p):-INF;
		int r_dis=x->rs?x->rs->Max_Distance(p):-INF;
		if( l_dis > r_dis )
		{
			if( x->ls && l_dis>ans )
				Get_Max(x->ls,p,ans);
			if( x->rs && r_dis>ans )
				Get_Max(x->rs,p,ans);
		}
		else
		{
			if( x->rs && r_dis>ans )
				Get_Max(x->rs,p,ans);
			if( x->ls && l_dis>ans )
				Get_Max(x->ls,p,ans);
		}
	}
}
int main()
{
	using namespace K_Dimension_Tree;
	int i;
	cin>>n;
	for(i=1;i<=n;i++)
		cin>>points[i];
	Build_Tree(root,1,n,0);
	for(i=1;i<=n;i++)
	{
		int min_dis=INF,max_dis=0;
		Get_Min(root,points[i],min_dis);
		Get_Max(root,points[i],max_dis);
		ans=min(ans,max_dis-min_dis);
	}
	cout<