HDU 1312 Red and Black

简单搜索题：

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
class Node
{
public:
     int x,y;
};
Node queue[424];
int d[4][2]={0,-1,1,0,0,1,-1,0};
char map[24][24];
int BFS( int x, int y )
{
   int end =0 ,first = 0;
   Node  t;
   t.x = x;
   t.y = y;
   queue[end]=t;
   end++;
   while( first < end )
   {
      for( int i=0; i<4 ; i++ )
      {
        int dx = queue[first].x + d[i][0];
        int dy = queue[first].y + d[i][1];
        if( map[dx][dy] == '.' )
        {
           t.x = dx;
           t.y = dy;
           map[dx][dy]='#';
           queue[end] =  t;
           end++;    
        }
      }
      first++;
   }    
   return end;
}
int main( )
{
   int n,m;
   while( scanf( "%d%d",&n,&m ),n )
   {
      memset( map , 0, sizeof( map ) );
      int x,y;
      for( int i = 1 ; i<= m ;i++ )
      {
          scanf( "%s",map[i]+1 );
          for( int j = 1; j<= n  ;j++ )
          {
              if( map[i][j]=='@' )
              {
                  x = i ;
                  y = j;
                  break;        
              }        
          }        
      }    
      map[x][y] = '#';
      printf( "%d\n",BFS( x , y ) );
   }
   return 0;
}