文艺平衡树

平衡树维护序列的板子题。
用\(fhqTreap\)
考虑在分裂时，用子树大小来分，因为我们相当要分裂出三个区间\([1,l - 1][l,r][r + 1,n]\)这个区间是按\(k_{th}\)分的，这个\(k_{th}\)指的的坐标序列。

文艺平衡树

#include<iostream>
#include<cstdio>
#include<cstdlib>
#define ll long long
#define M 10000010

ll ch[M][2],val[M],siz[M],lazy[M],key[M];

inline ll randdom(){return rand() << 15 | rand();}

#define ls(x) ch[x][0]
#define rs(x) ch[x][1]
#define v(x) val[x]
#define s(x) siz[x]
#define la(x) lazy[x]
#define c(x) key[x]

ll cnt;

inline ll newcode(ll x){
	v(++cnt) = x;
	s(cnt) = 1;
	la(cnt) = 0;
	c(cnt) = randdom();
//	std::cout<<randdom()<<std::endl;
	ls(cnt) = rs(cnt) = 0;
	return cnt; 
}

inline void up(ll x){
	s(x) = s(ls(x)) + s(rs(x)) + 1;	
}

inline void down(ll x){
	std::swap(ls(x),rs(x));
	la(x) = 0;
	if(ls(x))
	la(ls(x)) ^= 1;
	if(rs(x))
	la(rs(x)) ^= 1;
}

inline void split(ll now,ll k,ll &x,ll &y){
	if(!now){
		x = y = 0;
//		std::cout<<now<<" "<<k<<" "<<ls(now)<<" "<<rs(now)<<" "<<x<<" "<<y<<std::endl; 
		return ;
	}
	if(la(now))
	down(now);
	if(s(ls(now)) < k){
		x = now;
		split(rs(now),k - s(ls(now)) - 1,rs(now),y); 
	}else{
		y = now;
		split(ls(now),k,x,ls(now));
	}
//	std::cout<<now<<" "<<k<<" "<<ls(now)<<" "<<rs(now)<<" "<<x<<" "<<y<<std::endl; 
	up(now);
}

inline ll merge(ll x,ll y){//涉及到子树递归操作就要记得down 
//	std::cout<<x<<" "<<y<<""<<std::endl; 
	if(!x || !y)
	return x + y;
	if(c(x) < c(y)){
		if(la(x))
		down(x);
		rs(x) = merge(rs(x),y);
		up(x);
		return x; 
	}else{
		if(la(y))
		down(y);
		ls(y) = merge(x,ls(y));
		up(y);
		return y; 		
	} 
}

inline void print(ll now){
	if(!now)return;
	if(la(now))
	down(now);
	print(ls(now));
	std::cout<<v(now)<<" ";
	print(rs(now));
	return ; 
}

ll n,m,root;

int main(){
	scanf("%lld%lld",&n,&m);
	for(int i = 1;i <= n;++i)
		root = merge(root,newcode(i));
	for(int i = 1;i <= m;++i){
		ll l,r,x,y,z;//[1,l-1][l,r][r + 1,n]
		scanf("%lld%lld",&l,&r);
		split(root,l - 1,x,y);
//		std::cout<<x<<" "<<y<<std::endl;
		split(y,r - l + 1,y,z);
		la(y) ^= 1;
//		std::cout<<x<<" "<<y<<" "<<z<<std::endl;
		root = merge(x,merge(y,z));
//		std::cout<<root<<std::endl;
	}
	print(root);
	return 0;
}