ACM International Collegiate Programming Contest, Japan Domestic, 2004, Problem B

gistfile1.java

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.ListIterator;
/*
 * B.java
 *
 * Created on 2005/06/10, 2:05
 *
 * To change this template, choose Tools | Options and locate the template under
 * the Source Creation and Management node. Right-click the template and choose
 * Open. You can then make changes to the template in the Source Editor.
 */

/**
 *
 * @author kunishi
 */
public class B {
    
    public class Tile {
        public static final int RED = 0;
        public static final int BLACK = 1;
        public static final int OPEN = 1;
        public static final int CLOSE = 0;
        public int color;
        public int status;
        public int x, y;
        
        public Tile(int x, int y) {
            color = BLACK;
            status = CLOSE;
            this.x = x;
            this.y = y;
        }
        public Tile(int c, int x, int y) {
            color = c;
            status = CLOSE;
            this.x = x;
            this.y = y;
        }
        public int calc(Tile[][] tiles) {
            if (color == Tile.RED) {
                return 0;
            } else if (status == Tile.OPEN) {
                return 0;
            } else {
                int sum = 1;
                status = Tile.OPEN;
                ArrayList al = new ArrayList();
                al.add(tiles[x-1][y]);
                al.add(tiles[x][y+1]);
                al.add(tiles[x+1][y]);
                al.add(tiles[x][y-1]);
                ListIterator li = al.listIterator();
                while (li.hasNext()) {
                    sum += ((Tile)li.next()).calc(tiles);
                }
                return sum;
            }
        }
    }
    /** Creates a new instance of B */
    public B() {
    }
    
    public static void main(String[] args) {
        B b = new B();
        b.doCalculation(args[0]);
    }
    
    public void doCalculation(String file) {
        int w, h;
        Tile[][] tiles = null;
        Tile mypos = null;
        try {
            BufferedReader br = new BufferedReader(new FileReader(file));
            String s = br.readLine();
            while (!s.equals("0 0")) {
                w = Integer.parseInt(s.substring(0, s.indexOf(' ')));
                h = Integer.parseInt(s.substring(s.indexOf(' ')+1, s.length()));
                tiles = new Tile[w+2][h+2];
                for (int i = 0; i < h+2; i ++) {
                    tiles[0][i] = new Tile(Tile.RED, 0, i);
                    tiles[w+1][i] = new Tile(Tile.RED, w+1, i);
                }
                for (int i = 0; i < w+2; i ++) {
                    tiles[i][0] = new Tile(Tile.RED, i, 0);
                    tiles[i][h+1] = new Tile(Tile.RED, i, h+1);
                }
                for (int i = 0; i < h; i ++) {
                    s = br.readLine();
                    for (int j = 0; j < s.length(); j ++) {
                        switch (s.charAt(j)) {
                            case '.':
                                tiles[j+1][i+1] = new Tile(Tile.BLACK, j+1, i+1);
                                break;
                            case '#':
                                tiles[j+1][i+1] = new Tile(Tile.RED, j+1, i+1);
                                break;
                            case '@':
                                tiles[j+1][i+1] = new Tile(Tile.BLACK, j+1, i+1);
                                mypos = tiles[j+1][i+1];
                                break;
                            default:
                                break;
                        }
                    }
                }
                System.out.println(mypos.calc(tiles));
                s = br.readLine();
            }
        } catch (FileNotFoundException e) {
            System.out.println(e);
        } catch (IOException e) {
            System.out.println(e);
        }
    }
}