Red and Black（dfs水）

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1312

Red and Black

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 15186    Accepted Submission(s): 9401

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

6 9
....#.
.....#
......
......
......
......
......
#@...#
.#..#.
11 9
.#.........
.#.#######.
.#.#.....#.
.#.#.###.#.
.#.#..@#.#.
.#.#####.#.
.#.......#.
.#########.
...........
11 6
..#..#..#..
..#..#..#..
..#..#..###
..#..#..#@.
..#..#..#..
..#..#..#..
7 7
..#.#..
..#.#..
###.###
...@...
###.###
..#.#..
..#.#..
0 0

 

Sample Output

45
59
6
13

 

 #include<cstdio>
 #include<cstring>
 #include<algorithm>
 #include<string>
 using namespace std;
 #define N 25
 char mp[N][N];
 int go[][] = {{,},{-,},{,-},{,}};

 int n,m;
 bool ck(int x, int y){
     if(x<n&&x>=&&y<m&&y>=) return true;
     else return false;
 }
 bool vis[N][N];
 void dfs(int x, int y, int &sum)
 {
     vis[x][y] = ;
     bool fl = ;
     for(int i = ; i < ; i++){
         int xx = x + go[i][];
         int yy = y + go[i][];
         if(ck(xx,yy)&&!vis[xx][yy]&&mp[xx][yy]=='.'){
             fl = ;
             sum = sum+;
             dfs(xx,yy,sum);
         }
     }
     if(fl==) return;
 }
 int main()
 {
     while(~scanf("%d%d",&m,&n))
     {
         int x, y;
         if(n==&&m==) break;
         getchar();
         for(int i = ; i < n; i++){
             for(int j = ; j < m; j++){
                 scanf("%c",&mp[i][j]);
                 if(mp[i][j]=='@'){ x = i; y = j; }
             }
             getchar();
         }
         memset(vis,,sizeof(vis));
         int sum = ;
         dfs(x,y,sum);
         printf("%d\n",sum+);
     }
     return ;
 }