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
.#.........
.#.#######.
.#.#.....#.
.#.#.###.#.
.#.#[email protected]#.#.
.#.#####.#.
.#.......#.
.#########.
...........
11 6
..#..#..#..
..#..#..#..
..#..#..###
..#..#..#@.
..#..#..#..
..#..#..#..
7 7
..#.#..
..#.#..
###.###
[email protected]
###.###
..#.#..
..#.#..
0 0
Sample Output
45
59
6
13
dfs搜索，懒得解释，自己看代码。
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int n,m,ans;
char map[25][25];
int yi[4][2]={{1,0},{-1,0},{0,1},{0,-1}};
void dfs(int x,int y)
{
int i,rx,ry;
map[x][y]=‘#‘;
ans++;
for (i=0;i<4;i++)
{
rx=x+yi[i][0];
ry=y+yi[i][1];
if (rx>=1&&rx<=n&&ry>=1&&ry<=m&&map[rx][ry]==‘.‘)
{
dfs(rx,ry);
}
}
}
int main()
{
int i,j,x,y;
while (~scanf("%d%d",&m,&n))
{
if (n==0&&m==0) break;
ans=0;
for (i=1;i<=n;i++)
for (j=1;j<=m;j++)
{
scanf(" %c",&map[i][j]);
if (map[i][j]==‘@‘)
{
x=i;
y=j;
}
}
dfs(x,y);
printf("%d\n",ans);
}
return 0;
}