Red and Black（水）

Red and Black

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 12138    Accepted Submission(s):
7554

Problem Description

There is a rectangular room, covered with square tiles.
Each tile is colored either red or black. A man is standing on a black tile.
From a tile, he can move to one of four adjacent tiles. But he can't move on red
tiles, he can move only on black tiles.

Write a program to count the
number of black tiles which he can reach by repeating the moves described above.

 

Input

The input consists of multiple data sets. A data set
starts with a line containing two positive integers W and H; W and H are the
numbers of tiles in the x- and y- directions, respectively. W and H are not more
than 20.

There are H more lines in the data set, each of which includes W
characters. Each character represents the color of a tile as follows.

'.'
- a black tile
'#' - a red tile
'@' - a man on a black tile(appears
exactly once in a data set)

 

Output

For each data set, your program should output a line
which contains the number of tiles he can reach from the initial tile (including
itself).

 

Sample Input

 

Sample Output

45

59

6

13

 #include <iostream>
 #include <cstdio>
 using namespace std;
 char a[][];
 int m,n;
 int count=;
 void dfs(int x,int y)
 {
     if(a[x][y]=='.'&&x<n&&x>=&&y<m&&y>=)
     {
         count++;
         a[x][y]='#';
         dfs(x+,y);
         dfs(x,y+);
         dfs(x,y-);
         dfs(x-,y);
     }
 }
 int main()
 {
     freopen("in.txt","r",stdin);
     while(scanf("%d%d",&m,&n)&&m!=&&n!=)
     {
         count=;
         int i,j,x,y;
         for(i=;i<n;i++)
         {
             for(j=;j<m;j++)
             {
                 cin>>a[i][j];
                 if(a[i][j]=='@')
                 {
                     x=i;y=j;
                 }
             }
         }
         a[x][y]='.';
         dfs(x,y);
         cout<<count<<endl;
     }
 }