P3391 【模板】文艺平衡树(FHQ Treap)

#include<bits/stdc++.h>
using namespace std;
#define ls tr[u].l
#define rs tr[u].r
const int N=1e5+10;

//fast read,fast write
int read(){
	int x=0,f=1;char ch=getchar();
	while(ch<'0'||ch>'9'){
		if(ch=='-') f=-1;
		ch=getchar();
	}
	while(ch>='0'&&ch<='9') x=x*10+ch-'0',ch=getchar();
	return x*f;
}
void write(int x){
	if(x<0) putchar('-'),x=-x;
	if(x>9) write(x/10);
	putchar(x%10+'0');
}
void ot(int x){
	write(x),cout<<" ";
}

int n,m,root,idx;
struct node{
	int l,r;
	int val,key,sz,tag;
}tr[N];

int getnew(int v){
	tr[++idx].val=v,tr[idx].key=rand(),tr[idx].sz=1,tr[idx].tag=0;
	return idx;
}

void pushup(int u){
	tr[u].sz=tr[ls].sz+tr[rs].sz+1;
}

void pushdown(int u){
	if(!tr[u].tag) return;
	swap(ls,rs),tr[ls].tag^=1,tr[rs].tag^=1,tr[u].tag=0;
}

void split(int u,int k,int &x,int &y){
	if(!u){x=y=0;return;}
	pushdown(u);
	int res=tr[ls].sz+1;
	if(res<=k) x=u,split(rs,k-res,rs,y),pushup(x);
	else y=u,split(ls,k,x,ls),pushup(y);
}

int merge(int x,int y){
	if(!x||!y) return x+y;
	if(tr[x].key<tr[y].key){
		pushdown(x);
		tr[x].r=merge(tr[x].r,y);
		pushup(x);return x;
	}
	else{
		pushdown(y);
		tr[y].l=merge(x,tr[y].l);
		pushup(y);return y;
	}
}

void output(int u){
	if(!u) return;pushdown(u);
	output(ls),ot(tr[u].val),output(rs);
}

int main(){
	
	n=read(),m=read();
	for(int i=1;i<=n;i++) root=merge(root,getnew(i));
	while(m--){
		int l=read(),r=read(),x,y,z;
		split(root,r,x,z),split(x,l-1,x,y);
		tr[y].tag^=1,root=merge(merge(x,y),z);
	}
	output(root);
	
	return 0;
}