Crossword free response answer 2

Crossword free response problem from the 2016 AP Computer Science A Exam.

Crossword is #3 from the from the 2016 AP Computer Science A Free Response problems.

https://secure-media.collegeboard.org/digitalServices/pdf/ap/ap16_frq_computer_science_a.pdf

Part (a) – toBeLabeled method

private boolean toBeLabeled(int r, int c, boolean[][] blackSquares)
{
  if(blackSquares[r][c])
    return false;

  if(r == 0 || blackSquares[r - 1][c])
    return true;

  if(c == 0 || blackSquares[r][c - 1])
    return true;

  return false;
}

It is not acceptable to write the opposite checks and return false. The problem specifies that either or both of the conditions could be true for the square to be labeled.

Outside of an exam setting I would write this as:

return ! blackSquares[r][c] &&
    (r == 0 || blackSquares[r-1][c] || c == 0 || blackSquares[r][c-1]);

Part (b) – CrossWord constructor

public Crossword(boolean[][] blackSquares)
{
  puzzle = new Square[blackSquares.length][blackSquares[0].length];
  
  int num = 1;
  
  for(int r = 0; r < puzzle.length; r++)
  {
    for(int c = 0; c < puzzle[0].length; c++)
    {
      if(toBeLabeled(r, c, blackSquares))
      {
        puzzle[r][c] = new Square(false, num);
        num++;
      }
      else
        puzzle[r][c] = new Square(blackSquares[r][c], 0);
    }
  }
}