线段树-维护区间合并

题意：http://acm.hdu.edu.cn/showproblem.php?pid=1540

写了我老久

#define IOS ios_base::sync_with_stdio(0); cin.tie(0);
#include <cstdio>//sprintf islower isupper
#include <cstdlib>//malloc  exit strcat itoa system("cls")
#include <iostream>//pair
#include <fstream>//freopen("C:\Users\13606\Desktop\草稿.txt","r",stdin);
#include <bitset>
//#include <map>
//#include<unordered_map>
#include <vector>
#include <stack>
#include <set>
#include <string.h>//strstr substr
#include <string>
#include <time.h>//srand(((unsigned)time(NULL))); Seed n=rand()%10 - 0~9;
#include <cmath>
#include <deque>
#include <queue>//priority_queue<int, vector<int>, greater<int> > q;//less
#include <vector>//emplace_back
//#include <math.h>
//#include <windows.h>//reverse(a,a+len);// ~ ! ~ ! floor
#include <algorithm>//sort + unique : sz=unique(b+1,b+n+1)-(b+1);+nth_element(first, nth, last, compare)
using namespace std;//next_permutation(a+1,a+1+n);//prev_permutation
//******************
int abss(int a);
int lowbit(int n);
int Del_bit_1(int n);
int maxx(int a,int b);
int minn(int a,int b);
double fabss(double a);
void swapp(int &a,int &b);
clock_t __STRAT,__END;
double __TOTALTIME;
void _MS(){__STRAT=clock();}
void _ME(){__END=clock();__TOTALTIME=(double)(__END-__STRAT)/CLOCKS_PER_SEC;cout<<"Time: "<<__TOTALTIME<<" s"<<endl;}
//***********************
#define rint register int
#define fo(a,b,c) for(rint a=b;a<=c;++a)
#define fr(a,b,c) for(rint a=b;a>=c;--a)
#define mem(a,b) memset(a,b,sizeof(a))
#define pr printf
#define sc scanf
#define ls rt<<1
#define rs rt<<1|1
typedef long long ll;
const double E=2.718281828;
const double PI=acos(-1.0);
//const ll INF=(1LL<<60);
const int inf=(1<<30);
const double ESP=1e-9;
const int mod=(int)1e9+7;
const int N=(int)1e6+10;

struct node
{
    int l,r;
    int lmax,rmax,len;
}tr[N<<2];

void up(int rt)
{
    tr[rt].rmax=tr[rs].rmax;
    if(tr[rs].rmax==tr[rs].len)tr[rt].rmax=tr[rs].len+tr[ls].rmax;
    tr[rt].lmax=tr[ls].lmax;
    if(tr[ls].lmax==tr[ls].len)tr[rt].lmax=tr[ls].len+tr[rs].lmax;
}
void Build(int l,int r,int rt)
{
    tr[rt].l=l;
    tr[rt].r=r;
    tr[rt].len=r-l+1;
    tr[rt].lmax=tr[rt].rmax=r-l+1;
    if(l==r)return;
    int mid=l+r>>1;
    Build(l,mid,ls);
    Build(mid+1,r,rs);
//    up(rt);
}
void Delete(int pos,int l,int r,int rt)
{
    if(l==r)
    {
        tr[rt].lmax=tr[rt].rmax=0;
        return;
    }
    int mid=l+r>>1;
    if(pos<=mid)Delete(pos,l,mid,ls);
    else Delete(pos,mid+1,r,rs);
    up(rt);
}
void Rebuild(int pos,int l,int r,int rt)
{
    if(l==r)
    {
        tr[rt].lmax=tr[rt].rmax=1;
        return;
    }
    int mid=l+r>>1;
    if(pos<=mid)Rebuild(pos,l,mid,ls);
    else Rebuild(pos,mid+1,r,rs);
    up(rt);
}
int QnumL(int pos,int l,int r,int rt)
{
    if(pos>=r)return tr[rt].rmax;
    int mid=l+r>>1;
    if(pos>mid)
    {
        if(tr[rs].lmax<pos-tr[rs].l+1)
        {
            return max(QnumL(pos,mid+1,r,rs),tr[rs].rmax-(tr[rs].r-pos+1)+1);
        }
        else return pos-tr[rs].l+1+tr[ls].rmax;
    }
    else return QnumL(pos,l,mid,ls);
}
int QnumR(int pos,int l,int r,int rt)
{
    if(pos<=l)return tr[rt].lmax;
    int mid=l+r>>1;
    if(pos<=mid)
    {
        if(tr[ls].rmax<tr[ls].r-pos+1)
        {
            return max(QnumR(pos,l,mid,ls),tr[ls].lmax-(pos-tr[ls].l+1)+1);
        }
        else return tr[ls].r-pos+1+tr[rs].lmax;
    }
    else return QnumR(pos,mid+1,r,rs);
}

int op[N];
bool D[N];
int main()
{
    int n,m;
    while(~sc("%d%d",&n,&m))
    {
        int cnt=0;
        Build(1,n,1);
        for(int i=1;i<=n;++i)
            D[i]=1;
        for(int i=1;i<=m;++i)
        {
            char j[5];
            int pos=0;
            sc("%s",j);
            if(j[0]!='R')sc("%d",&pos);

            if(j[0]=='D')
                Delete(pos,1,n,1),op[++cnt]=pos,D[op[cnt]]=0;
            else if(j[0]=='Q')
            {
                if(D[pos]==0)
                {
                    pr("0
");
                    continue;
                }
                int ansl=QnumL(pos,1,n,1);
                int ansr=QnumR(pos,1,n,1);
                pr("%d
",ansl+ansr+(ansl||ansr?-1:0));
            }
            else Rebuild(op[cnt],1,n,1),D[op[cnt]]=1,cnt--;
        }
    }
    return 0;
}

/**************************************************************************************/

int maxx(int a,int b)
{
    return a>b?a:b;
}

void swapp(int &a,int &b)
{
    a^=b^=a^=b;
}

int lowbit(int n)
{
    return n&(-n);
}

int Del_bit_1(int n)
{
    return n&(n-1);
}

int abss(int a)
{
    return a>0?a:-a;
}

double fabss(double a)
{
    return a>0?a:-a;
}

int minn(int a,int b)
{
    return a<b?a:b;
}