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.
he 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)
The end of the input is indicated by a line consisting of two zeros. 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 题意：四方向，一起点，算黑砖数量 #include<iostream> #include<cstring> using namespace std; char G[25][25]; int W,H,x,y,sum; int step[4][2]={{1,0},{-1,0},{0,1},{0,-1}}; void dfs(int x,int y) { G[x][y]='#';sum++; for(int i=0;i<4;i++) { int nx=x+step[i][0],ny=y+step[i][1]; if(nx>=0&&nx<H&&ny>=0&&ny<W&&G[nx][ny]=='.') dfs(nx,ny); } } int main() { while(cin>>W>>H) { if(W==H&&H==0) break; for(int i=0;i<H;i++) for(int j=0;j<W;j++) { cin>>G[i][j]; if(G[i][j]=='@') x=i,y=j; } sum=0; dfs(x,y); cout<<sum<<endl; } return 0; }