P3391 【模板】文艺平衡树（Splay）

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#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;
const int MAXN=100001;
inline void read(int &n)
{	char c='+';int x=0;bool flag=0;
	while(c<'0'||c>'9'){c=getchar();if(c=='-')flag=1;}
	while(c>='0'&&c<='9'){x=x*10+(c-48);c=getchar();}
	n=flag==1?-x:x;
}
struct node
{
	int fa,ch[2];// 左右孩子 
	int size;//大小 
	bool rev; // 是否需要旋转
}tree[MAXN];
int root=0;
int n,m;
inline void update(int x)
{tree[x].size=tree[tree[x].ch[0]].size+tree[tree[x].ch[1]].size+1;}
inline void connect(int x,int f,bool how)
{tree[x].fa=f;	tree[tree[x].fa].ch[how]=x;}
inline void pushdown(int x)
{
	if(tree[x].rev)
		swap(tree[x].ch[0],tree[x].ch[1]),
		tree[tree[x].ch[0]].rev^=1,tree[tree[x].ch[1]].rev^=1,tree[x].rev=0;
}
int build(int l,int r)
{
	if(l>r)	return 0;
	int mid=(l+r)>>1;
	connect(build(l,mid-1),mid,0);	connect(build(mid+1,r),mid,1);
	tree[mid].rev=0;
	update(mid);	return mid;
}
inline bool get(int x)
{
	return tree[tree[x].fa].ch[1]==x;
}
inline int find(int x)
{
	--x;int now=root;pushdown(now);
	while(x!=tree[tree[now].ch[0]].size)
	{
		if(tree[tree[now].ch[0]].size<x)	x-=tree[tree[now].ch[0]].size+1,	now=tree[now].ch[1];
		else	now=tree[now].ch[0];
		pushdown(now);
	}
	return now;
}
inline void rotate(int x)
{
	int f=tree[x].fa;bool d=get(x);
	if(f==root)	root=x,tree[x].fa=0;
	else	connect(x,tree[f].fa,get(f));
	connect(tree[x].ch[!d],f,d);
	connect(f,x,!d);
	update(f);
}
inline void splay(int x,int r)
{
	if(x==r)	return ;
	for(int f;(f=tree[x].fa)!=r;)
	{
		if(tree[f].fa==r){rotate(x);break;}	
		rotate( (get(x)==get(f))?f:x );	rotate(x);
	}
	update(x);
}
inline void out(int x)
{
	if(!x)	return ;
	pushdown(x);
	out(tree[x].ch[0]);
	if(x!=1&&x!=n+2)	printf("%d ",x-1);
	out(tree[x].ch[1]);
}
int main()
{
	freopen("sph.in","r",stdin);
	freopen("sph.out","w",stdout);
	read(n);read(m);
	root=build(1,n+2);
	int l,r,tmp;
	for(int i=1;i<=m;i++)
	{
		read(l);read(r);
		splay(find(l),0);
		tmp=find(r+2);	splay(tmp,root);
		tree[tree[tmp].ch[0]].rev^=1;
	}
	out(root);
	return 0;
}