HDU 1540 Tunnel Warfare

该题与http://poj.org/problem?id=3667是同一类型的题目，这里就不多说了，因为HOTEL注释的比较详细。

#include<cstdio>
#include<iostream>
#include<vector>
using namespace std;
class Node 
{
public:
     int l,r;
     int l_value,r_value;
     int cover;    
};
Node tree[250024];
class Tree
{
public:
    void Maketree( int l,int r, int cnt );
    void Updata( int l,int r, int cnt,int num );
    void fun( int cnt );
    int Query( int cnt, int num );    
};
void Tree::Maketree( int l, int r, int cnt )
{
   tree[cnt].l = l;
   tree[cnt].r = r;
   tree[cnt].l_value = tree[cnt].r_value = r - l + 1;
   tree[cnt].cover = 0;
   if( l == r ) return ;
   else
   {
      int mid = ( l + r )>>1;
      Maketree( l ,mid , cnt*2 );
      Maketree( mid + 1 , r ,cnt*2+1 );        
   }    
}
void Tree::fun( int cnt )
{
   if( tree[cnt].cover==0 )
    tree[cnt].l_value=tree[cnt].r_value=tree[cnt].r -tree[cnt].l + 1;
   else tree[cnt].l_value = tree[cnt].r_value = 0;    
}
void Tree::Updata( int l, int r, int cnt , int num )
{
      if( r<tree[cnt].l||l>tree[cnt].r )
           return ;
    if( l<=tree[cnt].l&&r>=tree[cnt].r )
    {
       tree[cnt].cover  = num;
       fun( cnt );
       return ;    
    }
    else
    {
       if( tree[cnt].cover != -1 )
       {
           tree[cnt*2].cover = tree[cnt*2+1].cover = tree[cnt].cover;
           fun( cnt*2 );
           fun( cnt*2 +1 );    
           tree[cnt].cover = -1;
       }
       Updata( l , r, cnt*2 , num );
       Updata( l , r , cnt*2+1 , num );
      if( tree[cnt*2].cover==tree[cnt*2+1].cover )
          tree[cnt].cover = tree[cnt*2].cover;
      else tree[cnt].cover = -1;
      tree[cnt].l_value = tree[cnt*2].l_value + (tree[cnt*2].cover==0?tree[cnt*2+1].l_value:0);    
      tree[cnt].r_value = tree[cnt*2+1].r_value + ( tree[cnt*2+1].cover == 0? tree[cnt*2].r_value:0 );
    }
}
int Tree::Query( int cnt , int num )
{
    if( num >= tree[cnt].l&&tree[cnt].l+tree[cnt].l_value-1>=num )
          return     tree[cnt].l_value;
    if( num<=tree[cnt].r&&tree[cnt].r - tree[cnt].r_value+1 <= num )
          return tree[cnt].r_value;
    else
    {
       if( tree[cnt*2].r - tree[cnt*2].r_value+1 <= num&&tree[cnt*2+1].l+tree[cnt*2+1].l_value-1>=num )
         return tree[cnt*2+1].l_value + tree[cnt*2].r_value;
       else
       {
          if( tree[cnt].l<tree[cnt].r )
          {
              int mid = ( tree[cnt].l+tree[cnt].r )>>1;
              if( num<=mid  ) return Query( cnt*2 , num );
              else  return Query( cnt*2+1 , num );
          }        
       }
    }
    return 0;
}
int main( )
{
    int n,m,num;
    char c[2];
    
    while( scanf( "%d%d",&n,&m )==2 )
    {
       vector<int>S;
       Tree e;
       e.Maketree( 1 ,n ,1 );
       for( int i=0; i< m; i++ )
       {
           scanf( "%s",c );
           if( c[0]=='D' )
           {
              scanf( "%d",&num );
              S.push_back( num );
              e.Updata( num , num ,1 ,1 );        
           }        
           else
           {
                if( c[0]=='Q' )    
                {
                   scanf( "%d",&num );
                   printf( "%d\n",e.Query(1 ,num ) );    
                }
                else
                {
                   num = S.back();
                   S.pop_back();
                   e.Updata( num , num ,1, 0 );    
                }    
           }
       }    
    }
    return 0;
}