【hdu 1312】 Red and Black （dfs+bfs）

A - Red and Black

 

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

代码：

#include<cstdio>

int x_move[4]={0,0,1,-1};int y_move[4]={1,-1,0,0};int w,h,num,i,j;char map[25][25];void dfs(int x,int y){if(x<0||y<0||x>=w||y>=h)    return ;if(map[x][y]=='#')    return ;map[x][y]='#';num++;for(int i=0;i<4;i++)    dfs(x+x_move[i],y+y_move[i]);}int main(){while(~scanf("%d%d",&h,&w)&&h&&w){num=0;for(i=0;i<w;i++)   scanf("%s",map[i]);  for(i=0;i<w;i++){for(j=0;j<h;j++){if(map[i][j]=='@')dfs(i,j);}}printf("%d\n",num);}return 0;}