HDU 1312 Red and Black (DFS)

Red and Black

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 9795    Accepted Submission(s): 6103

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 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

 

Source

Asia 2004, Ehime (Japan), Japan Domestic

 

Recommend

Eddy

 

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#include<cstdio>
#include<iostream>
#include<cstring>
#include<stdlib.h>
#include<algorithm>
using namespace std;
const int MAXN=100;
int dir[4][2]={{0,1},{1,0},{0,-1},{-1,0}};
char map[MAXN][MAXN],s[MAXN];
int vis[MAXN][MAXN];
int ans,n,m;
void DFS(int x,int y)
{
    vis[x][y]=1;
    ans++;
    for(int i=0;i<4;i++)
    {
        int xx=x+dir[i][0];
        int yy=y+dir[i][1];
        if(0<=xx&&xx<n&&0<=yy&&yy<m&&!vis[xx][yy]&&map[xx][yy]!='#')
            DFS(xx,yy);
    }
}
int main()
{
    //freopen("in.txt","r",stdin);
    int x,y;
    while(scanf("%d %d%*c",&m,&n)&&(n||m))
    {
        for(int i=0;i<n;i++)
        {
            for(int j=0;j<m;j++)
            {
                scanf("%c",&map[i][j]);
                if(map[i][j]=='@')
                {
                    x=i;
                    y=j;
                }
            }
            getchar();
        }
        memset(vis,0,sizeof(vis));
        ans=0;
        DFS(x,y);
        printf("%d
",ans);
    }
    return 0;
}