四维偏序（K-D-Tree+rebuild）

其实只是放个代码，会K-D-Tree的同学看了就知道怎么rebuild了，其实也是很简单粗暴的……

单独再发一次吧，感觉把代码跟之前的一起发不知道啥时候就找不到了……

 #include<bits/stdc++.h>
 #define N 50010
 #define inf 1000000009
 #define lson (t1[o].l)
 #define rson (t1[o].r)
 using namespace std;
 typedef long long ll;
 int n,m,q[N],rt,dis,top=;int tot=,F;
 inline int read(){
     int f=,x=;char ch;
     do{ch=getchar();if(ch=='-')f=-;}while(ch<''||ch>'');
     do{x=x*+ch-'';ch=getchar();}while(ch>=''&&ch<='');
     return f*x;
 }int ans=;
 struct Point{
     int d[],maxv[],minv[],l,r,f,size,v,ma;
     inline int& operator [] (int x){return d[x];}
     inline int in(){for(int i=;i<;i++)d[i]=read();}
 }t1[N],t2[N],it;
 bool cmp(int a,int b){return t1[a][F]<t2[b][F];}
 bool operator < (Point a,Point b){
     for(int i=;i<=;i++){
         if(a.d[i]<b.d[i])return ;
         if(a.d[i]>b.d[i])return ;
     }
     return ;
 }
 inline void pushup(int o){
     for(int i=;i<=;i++){
         t1[o].minv[i]=min(t1[o].d[i],min(t1[lson].minv[i],t1[rson].minv[i]));
         t1[o].maxv[i]=max(t1[o].d[i],max(t1[lson].maxv[i],t1[rson].maxv[i]));
     }
     t1[o].ma=max(t1[o].v,max(t1[lson].ma,t1[rson].ma));
     t1[o].size=t1[lson].size+t1[rson].size+;
 }
     int build(int l,int r,int f){
         int mid=(l+r)>>;F=f;
         nth_element(q+l,q+mid,q+r+,cmp);
         int o=q[mid];t1[o].f=f;lson=;rson=;
         if(l<mid)lson=build(l,mid-,(f+)%);
         if(r>mid)rson=build(mid+,r,(f+)%);
         pushup(o);return o;
     }
     void dfs(int o){
         if(!o)return;q[++top]=o;
         dfs(lson);dfs(rson);
     }
     void rebuild(int &o){
         top=;dfs(o);
         o=build(,top,t1[o].f);
     }
     inline int newnode(int f){
         int o=++tot;t1[tot].f=f;t1[o]=it;
         for(int i=;i<=;i++)t1[o].minv[i]=t1[o].maxv[i]=t1[o][i];
         t1[o].ma=t1[o].v;t1[o].size=;
         return o;
     }
     void ins(int &o,int f){
         if(!o){o=newnode(f);return;}
         if(t1[o][f]<it[f]){
             ins(lson,(f+)%);
             pushup(o);
             if(t1[lson].size>t1[o].size*0.75)rebuild(o);
         }
         else{
             ins(rson,(f+)%);
             pushup(o);
             if(t1[rson].size>t1[o].size*0.75)rebuild(o);
         }
     }
     inline int check(int o){
         if(!o)return ;int _=;
         for(int i=;i<=;i++)if(t1[o].maxv[i]<=it.d[i])_++;
         if(_==)return _;
          _=;
         for(int i=;i<=;i++)if(t1[o].minv[i]>it[i])_=;
         return _;
     }
     inline int calcdis(Point x,Point y){
         for(int i=;i<=;i++)if(x[i]>y[i])return ;
         return x.v;
     }
     void query(int o){
         ans=max(calcdis(t1[o],it),ans);
         int dl=check(lson),dr=check(rson);
         if(dl==)ans=max(ans,t1[lson].ma);
         else if(dl&&ans<t1[lson].ma)query(lson);
         if(dr==)ans=max(ans,t1[rson].ma);
         else if(dr&&ans<t1[rson].ma)query(rson);
     }
 int main(){
     n=read();
     for(int i=;i<=;i++)t1[].minv[i]=inf,t1[].maxv[i]=-inf;
     t1[].ma=-inf;
     for(int i=;i<=n;i++){
         t2[i].in();t2[i].v=;
     }
     sort(t2+,t2+n+);
     int _=;
     for(int i=;i<=n;i++){
         ans=;it=t2[i];
         query(rt);
         t2[i].v+=ans;it=t2[i];
         _=max(_,t2[i].v);ins(rt,);
     }
     printf("%d\n",_);
 }