HPU:1312Red and Black(dfs)

Red and Black

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 14566    Accepted Submission(s): 9023

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

4559613
 
 
 
#include<cstdio>#include<cstring>char map[1010][1010];int vis[1010][1010];int m,n,sx,sy,ans;void dfs(int x,int y){if(x<0||x>=m||y<0||y>=n||vis[x][y]||map[x][y]=='#')return ;vis[x][y]=1;ans++;dfs(x+1,y);dfs(x,y+1);dfs(x-1,y);dfs(x,y-1);}int main(){while(scanf("%d%d",&n,&m)!=EOF){if(m==0&&n==0)break;memset(map,0,sizeof(map));memset(vis,0,sizeof(vis));ans=0;for(int i=0;i<m;i++){scanf("%s",map[i]);for(int j=0;j<n;j++){if(map[i][j]=='@')sx=i,sy=j;}}dfs(sx,sy);printf("%d\n",ans);}return 0;}