[NOI2005]维修数列

## [ 传送门 ](https://www.lydsy.com/JudgeOnline/problem.php?id=1500)

Solution

题意

维护一个数组，支持区间加点删点，区间覆盖，区间翻转，区间求和，求和最大的子序列

fhq模板题？
学完fhq后，就再也不爱打splay了 ......
注意回收点的时候要删标记，否则神奇MLE

Code

#include<bits/stdc++.h>
#define ll long long
#define max(a,b) ((a)>(b)?(a):(b))
#define min(a,b) ((a)<(b)?(a):(b))
inline 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<<3)+(x<<1)+ch-'0';ch=getchar();}
    return x*f;
}
#define MN 500005
#define inf 550000000 
int s[MN];
std::queue<int> q;
class fhq
{
    private:
        int sz;
        int pri[MN],ls[MN],rs[MN],siz[MN];
        int pr[MN],su[MN],tt[MN],cover[MN],V[MN],ans[MN];
        /*
		class QUEUE
		{
        	private:
				int q[MN<<3],top;		
			public:
				QUEUE(int _top=0):top(_top){}
				inline void push(int x){q[top]=x;(++top)%=MN;}
				inline bool empty(){return top==0;}
				inline int front(){return q[top-1];}
				inline void pop(){top--;}
		}q;
		*/
        bool rev[MN];
        inline unsigned int random()
        {
            static unsigned int x=23333;
            return x^=x<<13,x^=x>>17,x^=x<<5;
        }
        inline void up(int x)
        {
            siz[x]=1+siz[ls[x]]+siz[rs[x]];
            tt[x]=tt[ls[x]]+tt[rs[x]]+V[x];
            if(!ls[x]&&!rs[x]){pr[x]=su[x]=ans[x]=V[x];}
            else if(!ls[x])
            {
                pr[x]=V[x]+max(0,pr[rs[x]]);
                su[x]=max(su[rs[x]],tt[rs[x]]+V[x]);
                ans[x]=max(ans[rs[x]],pr[x]);
            }
            else if(!rs[x])
            {
                pr[x]=max(pr[ls[x]],tt[ls[x]]+V[x]);
                su[x]=V[x]+max(0,su[ls[x]]);
                ans[x]=max(ans[ls[x]],su[x]);
            }
            else
            {
                pr[x]=max(pr[ls[x]],tt[ls[x]]+V[x]+max(0,pr[rs[x]]));
            	su[x]=max(su[rs[x]],tt[rs[x]]+V[x]+max(0,su[ls[x]]));
            	ans[x]=max(ans[ls[x]],ans[rs[x]]);
            	ans[x]=max(ans[x],max(0,su[ls[x]])+V[x]+max(0,pr[rs[x]]));
            }

        }
        inline void update(int x,int opt)
        {
        	if(!x) return; 
        	if(opt==1)
            {
                std::swap(pr[x],su[x]);std::swap(ls[x],rs[x]);
                rev[ls[x]]^=1;rev[rs[x]]^=1;
            }
            if(opt==3)
            {
                V[x]=cover[x];tt[x]=cover[x]*siz[x];
                su[x]=pr[x]=ans[x]=max(cover[x],cover[x]*siz[x]);
                cover[ls[x]]=cover[rs[x]]=cover[x];
                rev[ls[x]]=rev[rs[x]]=0;
            }
        }
        inline void down(int x)
        {
        	if(cover[x]<inf) update(ls[x],3),update(rs[x],3),cover[x]=inf;
            if(rev[x]) update(ls[x],1),update(rs[x],1),rev[x]=0;
        }
        inline void recycle(int p)
		{
    		if(!p) return;
    		int L=ls[p],R=rs[p];
    		recycle(L);recycle(R);q.push(p);
    		ls[p]=rs[p]=rev[p]=0;
		}
	public:
        int rt;
        int Merge(int rt1,int rt2)
        {
        	if(rt1) down(rt1);
        	if(rt2) down(rt2);
            if(!rt1||!rt2) return rt2|rt1;
            if(pri[rt1]<pri[rt2])
            {
        		rs[rt1]=Merge(rs[rt1],rt2);
        		up(rt1);return rt1;
    		}
    		else
            {
        		ls[rt2]=Merge(rt1,ls[rt2]);
        		up(rt2);return rt2;
    		}
        }
        
        void Split(int x,int k,int&rt1,int&rt2)
        {
            if(!x) return (void)(rt1=rt2=0);
            down(x);
            if(k<=siz[ls[x]])
            {
                Split(ls[x],k,rt1,rt2);
                ls[x]=rt2;up(x);rt2=x;
            }
            else
            {
                Split(rs[x],k-siz[ls[x]]-1,rt1,rt2);
                rs[x]=rt1;up(x);rt1=x;
            }
        }
        void Build(int &x,int l,int r)
        {
            if(l>r) return;int mid=l+r>>1;
            if(!q.empty()) x=q.front(),q.pop();else x=++sz;
            ans[x]=tt[x]=V[x]=s[mid],cover[x]=inf,pri[x]=random();
            if(l==r) return(void)(pr[x]=su[x]=V[x],siz[x]=1);
            Build(ls[x],l,mid-1),Build(rs[x],mid+1,r);up(x);
        }
        void Reverse(int l,int len)
        {
        	register int rt1,rt2,rt3,rt4;
        	Split(rt,l-1,rt1,rt2);Split(rt2,len,rt3,rt4);
        	rev[rt3]^=1;update(rt3,1);rt=Merge(rt1,Merge(rt3,rt4));
        }
        void Replace(int l,int len,int c)
        {
            register int rt1,rt2,rt3,rt4;
        	Split(rt,l-1,rt1,rt2);Split(rt2,len,rt3,rt4);
        	cover[rt3]=c;update(rt3,3);rev[rt3]=0;rt=Merge(rt1,Merge(rt3,rt4));
        }
        void Delete(int l,int len)
        {
        	register int rt1,rt2,rt3,rt4;
        	Split(rt,l-1,rt1,rt2);Split(rt2,len,rt3,rt4);
        	rt=Merge(rt1,rt4);recycle(rt3);
        }
        void Insert(int pos,int r)
        {
            register int rt1,rt2,rt3;
            Split(rt,pos,rt1,rt2);Build(rt3,1,r);
            rt=Merge(rt1,Merge(rt3,rt2));
        }
        void QueSum(int l,int len)
        {
            register int rt1,rt2,rt3,rt4;
            Split(rt,l-1,rt1,rt2);Split(rt2,len,rt3,rt4);
            printf("%d
",tt[rt3]);rt=Merge(rt1,Merge(rt3,rt4));
        }
        void QueMax(){printf("%d
",ans[rt]);}
}T;
int main()
{
    register int i,n,m,posi,tot,c;
    register char ch[50];n=read();m=read();
    for(i=1;i<=n;++i) s[i]=read();
    T.Build(T.rt,1,n);
    while(m--)
    {
    	scanf("%s",ch+1);
    	if(ch[1]=='I')
    	{
    		posi=read();tot=read();
    		for(i=1;i<=tot;++i) s[i]=read();
    		T.Insert(posi,tot);
        }
        if(ch[1]=='D')
        {
            posi=read(),tot=read();
            T.Delete(posi,tot);
        }
        if(ch[1]=='M'&&ch[3]=='K')
        {
            posi=read();tot=read();c=read();
            T.Replace(posi,tot,c);
        }
        if(ch[1]=='R')
        {
            posi=read();tot=read();
            T.Reverse(posi,tot);
        }
        if(ch[1]=='G')
        {
            posi=read();tot=read();
            T.QueSum(posi,tot);
        }
        if(ch[1]=='M'&&ch[3]=='X'){T.QueMax();}
    }
    return 0;
}

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