ZOJ 2165 : Red and Black

zoj_2165.c

#include <stdio.h>
char tile[20][21];

int count_black(int i, int j, int w, int h) {
	int count = 0;
	if (tile[i][j] == '.' || tile[i][j] == '@') {
		count++;
		tile[i][j] = '#';
	}

	if (((i - 1) >= 0) && (tile[i-1][j] == '.'))
		count += count_black(i-1, j, w, h);
	if (((i + 1) < h) && (tile[i+1][j] == '.'))
		count += count_black(i+1, j, w, h);

	if (((j - 1) >= 0) && (tile[i][j-1] == '.')) 
		count += count_black(i, j-1, w, h);

	if (((j + 1) < w) && (tile[i][j+1] == '.'))
		count += count_black(i, j+1, w, h);
	return count;
}

int main() {
	int w, h, i, j, start_i, start_j;
	char c;
	scanf("%d %d", &w, &h);
	while(w != 0 && h != 0) {
		for(i = 0; i < h; ++i) {
				scanf("%s",tile[i]);
			for(j = 0; j < w; ++j) {
				if ( tile[i][j] == '@') {
					start_i = i;
					start_j = j;
				}
			}
		}
		printf("%d\n",count_black(start_i, start_j, w, h));
		scanf("%d %d", &w, &h);
	}
return 0;
}