題目：

Problem 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 integersW and H; W and H are the numbers of tiles in thex- 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
.#.........
.#.#######.
.#.#.....#.
.#.#.###.#.
.#.#

Sample Output

45
59
6
13

題目描述：

         搜尋當前子圖，簡單搜尋題。

解題程式碼：

#include<stdio.h> 
#include<string.h>
int f[110][110];
char e[110][110];
int a,b,c,i,j;
void q(int x,int y);
int main()
{
	
	while(scanf("%d%d",&a,&b),a !=0 || b != 0){
		c = 0;
		memset(f,0,sizeof(f));
		gets(e[105]);
		for(i = 0;i < b;i ++)
			gets(e[i]);
		for(i = 0;i < b;i ++){
			for(j = 0;j < a;j ++){
				if(e[i][j] == '@'){
					c = 1;
					break;
				}
			}
			if(c)
				break;
		}
		c = 0;
		q(i,j);
		f[i][j] = 1;
		printf("%d\n",c);
	}
	return 0;
}
void q(int x,int y)
{
	int i;
	int next[4][2]={0,1,
					1,0,
					0,-1,
					-1,0};
	e[x][y] = '-';
	c ++;
	for(i = 0;i < 4;i ++){
		int tx = x + next[i][0];
		int ty = y + next[i][1];
		if(tx >= b || tx < 0 || ty >= a || ty < 0 )
			continue;
		if(e[tx][ty] == '.' && !f[tx][ty]){
			f[tx][ty] = 1;
			q(tx,ty);
			
		}
	}
	return ;
}