package GoogleTreasureHunt2008;
import java.io.*;
import java.math.BigInteger;
import java.util.regex.Pattern;

public class GoogleTreasureHunt2 {
  public GoogleTreasureHunt2(String path, String a1, String b1, int l1, String a2, String b2, int l2) {
    File root = new File(path);
    System.out.println(sum(root, p(root, a1, b1), l1).multiply(sum(root, p(root, a2, b2), l2)));
  }
  private Pattern p(File root, String a, String b) {
    String pattern = root.getAbsolutePath() + "\\.*" + a + ".*" + b + "$";
    return Pattern.compile(pattern.replace("\\", "\\\\"));
  }
  private BigInteger sum(File dir, Pattern criteria, int line) {
    BigInteger result = BigInteger.ZERO;
    File[] files = dir.listFiles();
    for (File file : files)
      if (file.isDirectory())
        result = result.add(sum(file, criteria, line));
      else if (criteria.matcher(file.getAbsolutePath()).matches())
        result = result.add(lineToNumber(file, line));
    return result;
  }
  private BigInteger lineToNumber(File file, int line) {
    String l = null;
    BufferedReader reader = null;
    BigInteger result = BigInteger.ZERO;
    try {
      reader = new BufferedReader(new FileReader(file));
      for (int i = 1; (l = reader.readLine()) != null; i++) if (i == line) {
        result = new BigInteger(l);
        break;
      }
    } catch (Exception e) { ; }
    finally { try { reader.close(); } catch (Exception e) { ; } }
    return result;
  }
  public static void main(String[] args) {
    new GoogleTreasureHunt2("level2", "abc", ".pdf", 5, "yz1", ".pdf", 4);
  }
}

package GoogleTreasureHunt2008;
import java.math.BigInteger;

public class GoogleBotSolver
{
  private BigInteger[][] results;
  public GoogleBotSolver(int w, int h)
  {
    results = new BigInteger[w][h];
    for (int x = 0; x < w; x++)
    {
      for (int y = 0; y < h; y++)
      {
        results[x][y] = null;
      }
    }
    System.out.println(C(w - 1, h - 1).toString());
  }
  private BigInteger C(int x, int y)
  {
    if (results[x][y] != null) return results[x][y];
    BigInteger res;
    if (x == 0 && y == 0)
    {
      res = BigInteger.ZERO;
    }
    else if (x == 0 || y == 0)
    {
      res = BigInteger.ONE;
    }
    else
    {
      res = C(x - 1, y).add(C(x, y - 1));
    }
    results[x][y] = res;
    return res;
  }
  public static void main(String[] args)
  {
    GoogleBotSolver gbs = new GoogleBotSolver(38, 58);
  }
}

Svaret for W=38 og H=58 som herover er 194937478788574958222679204. Så robotten har rigtigt nok et par muligheder at vælge imellem.

Opgaven er iøvrigt en velkendt afart af Pascal’s trekant.