ZOJ Problem Set - 2165 Red and Black

ZOJ Problem Set - 2165

Red and Black

Time Limit: 2 Seconds Memory Limit: 65536 KB

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

#include<iostream>
#include<stdio.h>
#include<string.h>
#define MAX 30
using namespace std;
char map[MAX][MAX];
int count=0;
int w,h;
int dir[4][2]={{0,-1},{-1,0},{0,1},{1,0}};
void dfs(int r,int c)
{
//	cout<<"r: "<<r<<" c: "<<c<<endl;
//getchar();
if(r<=0||c<=0||r>h||c>w)
{
return;
}
map[r][c]='#';
for(int i=0;i<4;i++)
{
if(map[r+dir[i][0]][c+dir[i][1]]=='.')
{
//	map[r+dir[i][0]][c+dir[i][1]]='#';
count++;
dfs(r+dir[i][0],c+dir[i][1]);
//	map[r+dir[i][0]][c+dir[i][1]]='.';
}
}
}
int main()
{
while(cin>>w>>h)
{
if(w==0||h==0)break;
int sr,sc;
count=0;
memset(map,0,sizeof(map));
for(int i=1;i<=h;i++)
{
for(int j=1;j<=w;j++)
{
cin>>map[i][j];
if(map[i][j]=='@')
{
sr=i;sc=j;
}
}
}
map[sr][sc]='#';
//cout<<"Mark #1"<<endl;
dfs(sr,sc);
cout<<count+1<<endl;
}
}