Red and Black
| Time Limit: 1000MS | Memory Limit: 30000K | |
| Total Submissions: 30914 | Accepted: 16846 |
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.
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)
The end of the input is indicated by a line consisting of two zeros.
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.
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
Source
解析：简单DFS。
#include <cstdio>
int w, h;
char s[25][25];
int cnt;
bool inRoom(int x, int y)
{
return 0 <= x && x < h && 0 <= y && y < w;
}
void dfs(int x, int y)
{
if(inRoom(x, y) && s[x][y] == '.'){
++cnt;
s[x][y] = '#';
dfs(x-1, y);
dfs(x+1, y);
dfs(x, y-1);
dfs(x, y+1);
}
}
void solve()
{
int x, y;
for(int i = 0; i < h; ++i)
for(int j = 0; j < w; ++j)
if(s[i][j] == '@'){
x = i;
y = j;
s[i][j] = '.';
goto END;
}
END:
cnt = 0;
dfs(x, y);
printf("%d
", cnt);
}
int main()
{
while(scanf("%d%d", &w, &h), w){
for(int i = 0; i < h; ++i)
scanf("%s", s[i]);
solve();
}
return 0;
}