hdu1312 深搜 java

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

import java.util.Scanner;public class P1312 {    private static int dir[][]={{-1,0},{1,0},{0,-1},{0,1}};//上下左右    static long max=-1;    static long num=0;    static int h,w;    public static void main(String[] args) {        Scanner sc=new Scanner(System.in);        while(sc.hasNext()){            w=sc.nextInt();            h=sc.nextInt();            if(w==0&&h==0){                return;            }            char arr[][]=new char[h][w];            int x = 0,y=0;            int vistied[][]=new int[h][w];            for(int i=0;i<arr.length;i++){                String str=sc.next();                for(int j=0;j<arr[i].length;j++){                    arr[i][j]=str.charAt(j);                    vistied[i][j]=0;                    if(arr[i][j]=='@'){                        x=i;                        y=j;                    }                }            }            num=1;            dfs(arr, x, y,vistied);            System.out.println(num);        }    }    private static void dfs(char[][] arr,int a ,int b,int[][] vistied) {        for(int i=0;i<dir.length;i++){            int x=dir[i][0]+a;            int y=dir[i][1]+b;            if(inmap(x,y)&&arr[x][y]=='.'&&vistied[x][y]==0){                num++;                vistied[x][y]=1;                dfs(arr, x, y, vistied);            }        }    }    private static boolean inmap(int a, int b) {        if(a<0 || b<0 || a>=h || b>=w){                return false;            }            return true;    }}