poj 2892 &&hdu 1540 Tunnel Warfare

http://poj.org/problem?id=2892

 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 #define maxn 51000
 using namespace std;

 int stack1[maxn],top;
 struct node
 {
     int l,r;
     int len,ren;
 }p[maxn*];

 void up(int i)
 {
     p[i].len=p[i<<].len; p[i].ren=p[i<<|].ren;
     if(p[i<<].len==(p[i<<].r-p[i<<].l+))
         p[i].len+=p[i<<|].len;
     if(p[i<<|].ren==(p[i<<|].r-p[i<<|].l+))
         p[i].ren+=p[i<<].ren;
 }
 void build_tree(int i,int l,int r)
 {
     p[i].l=l; p[i].r=r;
     if(l==r)
     {
         p[i].len=p[i].ren=;
         return ;
     }
     int mid=(l+r)>>;
     build_tree(i<<,l,mid);
     build_tree(i<<|,mid+,r);
     up(i);
 }

 void update(int id,int i,int oper)
 {
     if(p[i].l==p[i].r)
     {
         p[i].len=p[i].ren=oper;
         return;
     }
     int mid=(p[i].l+p[i].r)>>;
     if(id<=mid)
         update(id,i<<,oper);
     else
         update(id,i<<|,oper);
     up(i);
 }

 int search1(int id,int i)
 {
     if(p[i].l==p[i].r)
         return p[i].len;
     int mid=(p[i].l+p[i].r)>>;
     if(id<=mid)
     {
         if(p[i<<].r-p[i<<].ren+<=id)
             return p[i<<].ren+p[i<<|].len;
         else
             search1(id,i<<);
     }
     else
     {
         if(p[i<<|].len+p[i<<|].l->=id)
             return p[i<<].ren+p[i<<|].len;
         else
             search1(id,i<<|);
     }
 }

 int main()
 {
     int n,q,a;
     while(scanf("%d%d",&n,&q)!=EOF)
     {
         build_tree(,,n);
         top=;
         getchar();
         while(q--)
         {
             char ch;
             scanf("%c",&ch);
             if(ch=='D')
             {
                 scanf("%d",&a);
                 update(a,,);
                 stack1[top++]=a;
             }
             else if(ch=='Q')
             {
                 scanf("%d",&a);
                 printf("%d\n",search1(a,));
             }
             else if(ch=='R')
             {
                 if(top>)
                 {
                     update(stack1[--top],,);
                 }
             }
             getchar();
         }
     }
     return ;
 }