HDU 1312 Red and Black (DFS)

  

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

要小心它的输入

行列是相反的

坑在这里找了好多次TAT

#include<stdio.h>
#include<iostream>
using namespace std;
char map[25][25];
int n,m;
int num;
int rx[]={0,0,1,-1};
int ry[]={1,-1,0,0};
void dfs(int i,int j)
{
    map[i][j]='#';
    num++;
    int t,x,y;
    for(t=0;t<4;t++)
    {
        x=i+rx[t];
        y=j+ry[t];
        if(x>=0 && x<n && y>=0 && y<m && map[x][y]=='.')
            dfs(x,y);    
    }
}
int main()
{
    int i,j;
    int si,sj;
    while(scanf("%d%d",&m,&n)!=EOF)//原来是行数和列数反了...我真是醉了....
    {
        
        if(m==0&&n==0)break;
        for(i=0;i<n;i++)
            for(j=0;j<m;j++)
            {
                cin>>map[i][j];
                if(map[i][j]=='@')
                {
                    si=i;
                    sj=j;
                }
            }
        num=0;
        dfs(si,sj);
        printf("%d
",num);
    }
    return 0;
}