class C4State {
  private static boolean[][][] map;
  private int[][]              score = new int[2][winPlaces];
  public static final int      winPlaces = 69, maxPieces = 42, Empty = 2;
  private int                  numPieces;
  public int[][]               board = new int[7][6];

  public C4State() {
    // Initialize the map
    int i, j, k, count = 0;
    if (map == null) {
      map = new boolean[7][6][winPlaces];
      for (i = 0; i < 7; i++)
        for (j = 0; j < 6; j++)
          for (k = 0; k < winPlaces; k++)
            map[i][j][k] = false;

      // Set the horizontal win positions
      for (i = 0; i < 6; i++)
        for (j = 0; j < 4; j++) {
          for (k = 0; k < 4; k++)
            map[j + k][i][count] = true;
          count++;
        }
    
      // Set the vertical win positions
      for (i = 0; i < 7; i++)
        for (j = 0; j < 3; j++) {
          for (k = 0; k < 4; k++)
            map[i][j + k][count] = true;
          count++;
        }

      // Set the forward diagonal win positions
      for (i = 0; i < 3; i++)
        for (j = 0; j < 4; j++) {
          for (k = 0; k < 4; k++)
            map[j + k][i + k][count] = true;
          count++;
        }

      // Set the backward diagonal win positions
      for (i = 0; i < 3; i++)
        for (j = 6; j >= 3; j--) {
          for (k = 0; k < 4; k++)
            map[j - k][i + k][count] = true;
          count++;
        }
    }

    // Initialize the board
    for (i = 0; i < 7; i++)
      for (j = 0; j < 6; j++)
        board[i][j] = Empty;

    // Initialize the scores
    for (i = 0; i < 2; i++)
      for (j = 0; j < winPlaces; j++)
        score[i][j] = 1;

    numPieces = 0;
  }

  public boolean isWinner(int player) {
    // See whether the player has won
    for (int i = 0; i < winPlaces; i++)
      if (score[player][i] == 16)
        return true;
    return false;
  }

  public boolean isTie() {
    // See whether there is a tie
    return (numPieces == maxPieces);
  }

  public int dropPiece(int player, int xPos) {
    // See whether the slot has room for the piece
    int yPos = 0;
    while ((board[xPos][yPos] != Empty) && (++yPos < 6))
      ;

    // The slot is full
    if (yPos == 6)
      return -1;

    // The slot has room, so drop the piece
    board[xPos][yPos] = player;
    numPieces++;
    updateScore(player, xPos, yPos);
    return yPos;
  }

  private void updateScore(int player, int x, int y) {
    // Update the score for the specified piece
    for (int i = 0; i < winPlaces; i++)
      if (map[x][y][i]) {
        score[player][i] <<= 1;
        score[1 - player][i] = 0;
      }
  }
}