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.
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)
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).
#include <iostream>
#include <cstdio>
#include <cstring>
using namespace::std;
int s_i,s_j,num;
char maps[25][25];
int maps_[25][25]={0},a[4][2] = {{1,0},{-1,0},{0,1},{0,-1}};
int W,H;
void dfs(int n,int m)
{
for(int i=0;i<4;i++)
{
int x = n + a[i][0];
int y = m + a[i][1];
if(x>=0 && y>=0 && x<H && y<W && maps_[x][y] != 1 && maps[x][y] != ‘#‘)
{
num++;
maps_[x][y] = 1;
dfs(x,y);
}
}
}
int main()
{
int i,j;
while(scanf("%d %d",&W,&H) && W != 0 && H != 0)
{
memset(maps,0,sizeof(maps)); //每次输入清空地图和标记
memset(maps_,0,sizeof(maps_));
for(i=0;i<H;i++)
{
scanf("%s",&maps[i]);
for(j =0;j<W;j++)
{
if(maps[i][j] == ‘@‘) //找到起始点
{
s_i = i;
s_j = j;
break;
}
}
}
num = 1;
maps_[s_i][s_j] = 1; //标记起始点
dfs(s_i,s_j);
printf("%d\n",num);
}
return 0;
}
