题目大意：维护一种数据结构，支持下列操作：

1.将一个区间加上一个数

2.将一个区间翻转

3.询问一段区间的最大值

Splay裸题 OTZ题干……

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#define M 50500
using namespace std;
struct abcd{
	abcd *ls,*rs,*fa;
	int num,max_num;
	int size;
	int add_mark;
	bool rev_mark;
	void Push_Up();
	void Push_Down();
	void Add(int x);
	void Reverse();
	abcd(int x);
}*null=new abcd(0xefefefef),*root;
int n,m;
abcd :: abcd(int x)
{
	ls=rs=fa=null;
	num=max_num=x;
	size=null?1:0;
	add_mark=0;
	rev_mark=0;
}
void abcd :: Push_Up()
{
	size=ls->size+rs->size+1;
	max_num=max( max(ls->max_num,rs->max_num),num );
}
void abcd :: Push_Down()
{
	if(rev_mark)
	{
		ls->Reverse();
		rs->Reverse();
		rev_mark=0;
	}
	if(add_mark)
	{
		ls->Add(add_mark);
		rs->Add(add_mark);
		add_mark=0;
	}
}
void abcd :: Add(int x)
{
	if(this==null)
		return ;
	num+=x;
	max_num+=x;
	add_mark+=x;
}
void abcd :: Reverse()
{
	swap(ls,rs);
	rev_mark^=1;
}
void Zig(abcd *x)
{
	abcd *y=x->fa;
	y->ls=x->rs;
	x->rs->fa=y;
	x->rs=y;
	x->fa=y->fa;
	if(y==y->fa->ls)
		y->fa->ls=x;
	else if(y==y->fa->rs)
		y->fa->rs=x;
	y->fa=x;
	y->Push_Up();
	if(y==root)
		root=x;
}
void Zag(abcd *x)
{
	abcd *y=x->fa;
	y->rs=x->ls;
	x->ls->fa=y;
	x->ls=y;
	x->fa=y->fa;
	if(y==y->fa->ls)
		y->fa->ls=x;
	else if(y==y->fa->rs)
		y->fa->rs=x;
	y->fa=x;
	y->Push_Up();
	if(y==root)
		root=x;
}
void Splay(abcd *x,abcd *tar)
{
	while(1)
	{
		abcd *y=x->fa,*z=y->fa;
		if(y==tar)
			break;
		if(z==tar)
		{
			if(x==y->ls)
				Zig(x);
			else
				Zag(x);
			break;
		}
		if(x==y->ls)
		{
			if(y==z->ls)
				Zig(y);
			Zig(x);
		}
		else
		{
			if(y==z->rs)
				Zag(y);
			Zag(x);
		}
	}
	x->Push_Up();
}
void Find(abcd *x,int y,abcd *z)
{
	while(1)
	{
		int temp=x->ls->size;
		x->Push_Down();
		if(y<=temp)
			x=x->ls;
		else
		{
			y-=temp;
			if(y==1)
				break;
			--y;
			x=x->rs;
		}
	}
	Splay(x,z);
}
abcd* Build_Tree(int x,int y)
{
	int mid=x+y>>1;
	if(x>y) return null;
	abcd *re=new abcd(0);
	re->ls=Build_Tree(x,mid-1);
	re->rs=Build_Tree(mid+1,y);
	re->ls->fa=re->rs->fa=re;
	return re->Push_Up(),re;
}
void Initialize()
{
	root=new abcd(19980402);
	root->rs=new abcd(19980402);
	root->rs->ls=Build_Tree(1,n);
	root->rs->ls->fa=root->rs;
	root->rs->fa=root;
	root->rs->Push_Up();
	root->Push_Up();
}
void Add()
{
	int x,y,z;
	scanf("%d%d%d",&x,&y,&z);
	Find(root,x,null);
	Find(root,y+2,root);
	root->rs->ls->Add(z);
}
void Reverse()
{
	int x,y;
	scanf("%d%d",&x,&y);
	Find(root,x,null);
	Find(root,y+2,root);
	root->rs->ls->Reverse();
}
void Query()
{
	int x,y;
	scanf("%d%d",&x,&y);
	Find(root,x,null);
	Find(root,y+2,root);
	printf("%d\n",root->rs->ls->max_num);
}
int main()
{
	int i,p;
	cin>>n>>m;
	Initialize();
	for(i=1;i<=m;i++)
	{
		scanf("%d",&p);
		switch(p)
		{
			case 1:Add();break;
			case 2:Reverse();break;
			case 3:Query();break;
		}
	}
}

BZOJ 1251 序列终结者 Splay