ZOJ Problem Set

http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=1165

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

1. “.”：黑色的瓷砖；

2. “#”：白色的瓷砖；

3. “@”：黑色的瓷砖，并且一个人站在这块瓷砖上。

计算总共能够到达多少块黑色的瓷砖。

#include<stdio.h>
int x,y,i,j;
char a[30][30];
int f(int i,int j)
{
	if(i<0||j<0||i>=x||j>=y)
	return 0;
	if(a[i][j]=='#')
	return 0;
	else{
		a[i][j]='#';
		return 1+f(i+1,j)+f(i-1,j)+f(i,j+1)+f(i,j-1);
	}
}
int main()
{	
	while(scanf("%d%d",&y,&x),x!=0||y!=0)
	{
		for(i=0;i<x;i++)
		    scanf("%s",a[i]);
		for(i=0;i<x;i++)
		    for(j=0;j<y;j++)
		        if(a[i][j]=='@')
		            printf("%d
",f(i,j));
	}
	return 0;
}