Treap

#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
const int INF = 1e9 + 7;

int R,node,ls[N],rs[N],val[N],rd[N],sz[N],n;

void push(int x){sz[x] = sz[ls[x]] + sz[rs[x]] + 1 ;}

void spl(int p,int v,int &x,int &y){
    if(!p)return x=y=0,void();
    if(val[p]<=v)spl(rs[p],v,rs[x=p],y);
    else spl(ls[p],v,x,ls[y=p]);
    push(p);
}

int mer(int x, int y){
    if(!x||!y)return x|y;
    if(rd[x] < rd[y])return ls[y] = mer(x,ls[y]),push(y),y;
    return rs[x] = mer(rs[x],y),push(x),x;
}

int nd(int v){
    int x = ++ node;
    val[x] = v,rd[x] = rand();sz[x] = 1;
    return x;
}
void ins(int v){
    int x = 0,y = 0;
    spl(R,v-1,x,y),R = mer(mer(x,nd(v)),y);
}

void del(int v){
    int x = 0, y = 0, z= 0;
    spl(R,v,x,z),spl(x,v-1,x,y);
    R = mer(mer(x,y = mer(ls[y],rs[y])),z);
}

int pre(int v){
    int p = R,ans = 0;
    while(1){
    if(!p)return ans;
    else if(v <= val[p])p = ls[p];
    else ans = val[p],p=rs[p];
    }
}

int suc(int v){
    int p = R,ans = 0;
    while(1){
        if(!p)return ans;
        else if(v>=val[p])p=rs[p];
        else ans = val[p],p=ls[p];
    }

}
int kth(int k){
	int p=R;
	while(1){
		if(k<=sz[ls[p]])p=ls[p];
		else if(k==sz[ls[p]]+1)return val[p];
		else k-=sz[ls[p]]+1,p=rs[p];
	}
}

int rnk(int v){
    int x=0,y=0,ans=0;
    spl(R,v-1,x,y),ans=sz[x]+1;
    return R=mer(x,y),ans;


}
int main()
{
    //freopen("P3369.in","r",stdin);
	cin>>n;
	for(int i=1;i<=n;i++){
		int op,x; cin>>op>>x;
		if(op==1)ins(x);
		if(op==2)del(x);
		if(op==3)cout<<rnk(x)<<endl;
		if(op==4)cout<<kth(x)<<endl;
		if(op==5)cout<<pre(x)<<endl;
		if(op==6)cout<<suc(x)<<endl;
	}
	return 0;

}
cpp

标签：sz,val,rs,int,Treap,ls,op
来源： https://www.cnblogs.com/ErFu/p/16491767.html