ZOJ 2165 Red and Black

1.采用dfs：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
using namespace std;
char map[25][25];
int count = 1;
int r,c;
int dx[4] = {1,-1,0,0};
int dy[4] = {0,0,1,-1};
bool judge(int x,int y)
{
    if(x<0 || x>= r || y < 0 ||y>=c)
        return 0;
    return 1;
}
void dfs(int x,int y)
{
    map[x][y] = '#';
    int nx = 0;
    int ny = 0;
    for(int i = 0 ; i < 4; i++)
    {
        nx = x + dx[i];
        ny = dy[i] + y;
        if(!judge(nx,ny))
            continue;
        if(map[nx][ny] == '.')
        {
            count++;
            dfs(nx,ny);
        }
    }
}
int main()
{
    //freopen("test.in", "r", stdin);
    while(cin>>c>>r && r&&c)
    {
        count = 1;
        int x0,y0;
        for(int i = 0; i < r; i++ )
        {
            for(int j = 0 ; j < c; j++)
            {
                cin>>map[i][j];
                if(map[i][j] == '@')
                {
                    x0 = i;
                    y0 = j;
                }
            }
        }
        dfs(x0,y0);
        cout<<count<<endl;
    }
    return 0;
}

2.bfs:

#include <iostream>
#include <queue>
using namespace std;
structnode { int r; int l;};
int m, n, sr, sl;
int dir[2][4] = {{-1, 1, 0, 0}, {0, 0, -1, 1}};
int visited[20][20];
int BFS();
int main()
{ 
    int i, j; 
    char str[21]; 
    while(cin >> m >> n)
     {	 
         if(m == 0 || n == 0)
          {	
               break;	
          }	
         for(i = 0; i < n; i++)
          {	 
              cin >> str;
              for(j = 0; j < m; j++) 
              {	
                if(str[j] == '@')
                  {	
                    sr = i;	
                    sl = j;	
                    visited[i][j] = 1;	
                  }	
                      
                    else if(str[j] == '.') 
                        {
                            	 visited[i][j] = 0;	
                        } 
                         else 
                         {	
                              visited[i][j] = 1;
                         }	
                      
                } 
            }

           	 int count = BFS();	 
           	 cout << count << endl;
      } 
           	  return 0;
  }
  int BFS()
  { 
      int i, count; 
      queue<node>Q; 
      nodeN, temp; 
      N.r = sr; 
      N.l = sl;
       count = 1;
        Q.push(N); 
  while(!Q.empty())
    {	 
             temp = Q.front();
         	 Q.pop();
        for(i = 0; i < 4; i++)
            {	
                   N = temp;	
                   N.r += dir[0][i];	
         	  	   N.l += dir[1][i];
         	 	   	 if(N.r < 0 || N.r >= n ||	 N.l < 0 || N.l >= m) 
         	 	   	 {	
         	 	   	      continue;	
                     } 
         	 	   	  else 
         	 	   	  {	 
         	 	   	      if(!visited[N.r][N.l])
         	 	   	       {	
         	 	   	            count++;
                                visited[N.r][N.l] = 1;
                                Q.push(N);	
                           }	
                      }
         	 	   	            	
            }
    } 
return count;
}