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
dfs练习题 求与 @可走的.个数 本身也算
#include <iostream> #include <stdio.h> #include <string.h> #include <algorithm> using namespace std; #define N 22 int dir[4][2]={-1,0,1,0,0,-1,0,1}; char map[N][N]; int cnt; int h,w; bool ok(int x,int y) { if(x<0||x>=h) return false; if(y<0||y>=w) return false; if(map[x][y]=='#') return false; return true; } void dfs(int a,int b) { cnt++; map[a][b]='#'; int i; int x,y; for(i=0;i<4;i++) { x=a+dir[i][0]; y=b+dir[i][1]; if(ok(x,y)) { dfs(x,y); } } } int main() { int i,j; int s,t; while(scanf("%d %d",&w,&h),h||w) { getchar(); for(i=0;i<h;getchar(),i++) for(j=0;j<w;j++) { scanf("%c",&map[i][j]); if(map[i][j]=='@') s=i,t=j; } cnt=0; dfs(s,t); printf("%d\n",cnt); } return 0; }