【转】poj 1823

#include<iostream>

#include<fstream>

 

using namespace std;

 

struct e{

    int l,r,cnt,cntl,cntr;

    int state;

};

 

e tree[48001];

 

 

int n,m;

 

void build(int s,int t,int p){

    int i,j,k;

    tree[p].l=s;tree[p].r=t;

    tree[p].state=-1;

    tree[p].cnt=tree[p].cntl=tree[p].cntr=t-s+1;

    if(s==t) return;

    else

    {

        k=(s+t)>>1;

        build(s,k,2*p);

        build(k+1,t,2*p+1);

    }

}

 

void godown(int p,int value){

    tree[p].state=0;

    tree[2*p].state=tree[2*p+1].state=value;

    if(value==-1)

    {

        tree[2*p].cnt=tree[2*p].cntl=tree[2*p].cntr=tree[2*p].r-tree[2*p].l+1;

        tree[2*p+1].cnt=tree[2*p+1].cntl=tree[2*p+1].cntr=tree[2*p+1].r-tree[2*p+1].l+1;

    }

    else

    {

        tree[2*p].cnt=tree[2*p].cntl=tree[2*p].cntr=0;

        tree[2*p+1].cnt=tree[2*p+1].cntl=tree[2*p+1].cntr=0;

    }

}

 

 

void update(int s,int t,int p,int value){

    int i,j,k;

    if(s<=tree[p].l&&tree[p].r<=t)

    {

        tree[p].state=value;

        if(value==-1)

        {

            i=tree[p].r-tree[p].l+1;

            tree[p].cnt=tree[p].cntl=tree[p].cntr=i;

        }

        else

            tree[p].cnt=tree[p].cntl=tree[p].cntr=0;

        return;

    }

    if(tree[p].state==value) return;

    if(tree[p].state==-value) godown(p,-value);

     

    if(t<=tree[p*2].r) update(s,t,2*p,value);

    else

        if(s>=tree[2*p+1].l) update(s,t,2*p+1,value);

        else

        {

            update(s,t,2*p,value);

            update(s,t,2*p+1,value);

        }

 

    if(tree[2*p].state==-1)

        tree[p].cntl=tree[2*p].cnt+tree[2*p+1].cntl;

    else

        tree[p].cntl=tree[2*p].cntl;

     

    if(tree[2*p+1].state==-1)

        tree[p].cntr=tree[2*p+1].cnt+tree[2*p].cntr;

    else

        tree[p].cntr=tree[2*p+1].cntr;

     

    if(tree[2*p+1].state==tree[2*p].state)

        tree[p].state=tree[2*p].state;

     

    i=tree[2*p].cntr+tree[2*p+1].cntl;

    j=max(tree[2*p].cnt,tree[2*p+1].cnt);

    tree[p].cnt=max(max(i,j),k);

}

 

void read(){

//  ifstream cin("in.txt");

    int i,j,k,s,t;

//  cin>>n>>m;

    scanf("%d%d",&n,&m);

    build(1,n,1);

    for(i=1;i<=m;i++)

    {

    //  cin>>j;

        scanf("%d",&j);

        if(j==1)

        {

        //  cin>>s>>t;

            scanf("%d%d",&s,&t);

            update(s,s+t-1,1,1);

        }

        else

            if(j==2)

            {

            //  cin>>s>>t;

                scanf("%d%d",&s,&t);

                update(s,s+t-1,1,-1);

            }

            else

                cout<<tree[1].cnt<<endl;

    }

}

 

int main(){

    read();

    return 0;

}