Find word letter grid

Question

I'm working on Boggle game and I'm creating a method called findWord which return true if "word" can be found in "grid". return false otherwise private member variable grid has the letter grid. however, when i run my main method it keeps print out "not found" and I couldn't figere out where i made a mistake! this is my code

  public class BoggleGame_old {
  LetterGrid grid;
  private char[][]board;
  boolean[][] visited;
 public BoggleGame_old(LetterGrid g) 
{
    grid = g;
}
public boolean findWord(String word) {

    for(int row=0;row<this.board.length;row++){
        for(int col=0;col<this.board.length;col++){
            if(this.find(word, row, col)){
                return true;
            }
        }
    }
    return false; 
}
   //helping function
   private boolean find(String word, int row, int col){
    if(word.equals(""))
    {
        return true;
    }
    else if(row<0||row>=this.board.length||

            col<0||col>=this.board.length||
            this.board[row][col] != word.charAt(0))
    {
        return false;

    }
    else{
        char c=this.board[row][col];
        this.board[row][col]='*';
        String curr=word.substring(1,word.length());
        boolean res=this.find(curr, row-1, col-1)||
                this.find(curr, row-1, col)||
                this.find(curr, row-1, col+1)||
                this.find(curr, row, col-1)||
                this.find(curr, row, col+1)||
                this.find(curr, row+1, col-1)||
                this.find(curr, row+1, col)||
                this.find(curr, row+1, col);
             this.board[row][col]=c;
             return res;
    }


}

The condition in your inner for-loop should be `col < this.board[row].length;` (you can omit the `this`. It's redundant since there is no ambiguity). — RaminS, Jul 15 '16 at 15:31
Same for second if, second or condition in helping function (only allowed exception, but not good practice: if board is guaranteed to have square size). — Aconcagua, Jul 15 '16 at 15:37

score 0 · Answer 1 · answered Jul 15 '16 at 16:01

One issue I see is that you call this.find(curr, row+1, col) twice, the second one should be this.find(curr, row+1, col+1). It would stop you from being able to check diagonally down/right, without seeing test cases I can't say if that's actually causing it to always fail.

Aconcagua · Answer 2 · 2016-07-15T16:39:03.710

You might find this interesting, it finds words horizontally, vertically and diagonally (but not in reverse direction):

public boolean findWord(String word)
{
    if(word == null || word.isEmpty())
        return true;
    int rowMax = board.length - word.length();
    int colMax = board[0].length - word.length();
    if(rowMax < 0 || colMax < 0)
        return false;
    for (int row = 0; row < rowMax; ++row)
    {
        for (int col = 0; col < colMax; ++col)
        {
            boolean v = true;
            boolean h = true;
            boolean d = true;
            for(int c = 0; c < word.length(); ++c)
            {
                v &= board[row + c][col] == word.charAt(c);
                h &= board[row][col + c] == word.charAt(c);
                d &= board[row + c][col + c] == word.charAt(c);
                if(!(v | h | d))
                    break;
            }
            if(v|h|d)
                return true;
        }
    }
    return false;
}

Edit: Variant finding strings in opposite direction, too:

public boolean findWord(String word)
{
    if(word == null || word.isEmpty())
        return true;
    int rowMax = board.length - word.length();
    int colMax = board[0].length - word.length();
    if(rowMax < 0 || colMax < 0)
        return false;
    StringBuilder reverse = new StringBuilder(word).reverse();
    for (int row = 0; row < rowMax; ++row)
    {
        for (int col = 0; col < colMax; ++col)
        {
            boolean v = true;
            boolean h = true;
            boolean d = true;
            boolean rv = true;
            boolean rh = true;
            boolean rd = true;
            for(int c = 0; c < word.length(); ++c)
            {
                v &= board[row + c][col] == word.charAt(c);
                h &= board[row][col + c] == word.charAt(c);
                d &= board[row + c][col + c] == word.charAt(c);
                rv &= board[row + c][col] == reverse.charAt(c);
                rh &= board[row][col + c] == reverse.charAt(c);
                rd &= board[row + c][col + c] == reverse.charAt(c);
                if(!(v | h | d | rv | rh | rd))
                    break;
            }
            if(v | h | d | rv | rh | rd)
                return true;
        }
    }
    return false;
}

Edit 2: So many booleans... – a little bit compacter:

int flags = 0;
for(int c = 0; flags != 0b111111 && c < word.length(); ++c)
{
    flags |= board[row + c][col    ] == word.charAt(c)    ? 0 : 1 << 0;
    flags |= board[row    ][col + c] == word.charAt(c)    ? 0 : 1 << 1;
    flags |= board[row + c][col + c] == word.charAt(c)    ? 0 : 1 << 2;
    flags |= board[row + c][col    ] == reverse.charAt(c) ? 0 : 1 << 3;
    flags |= board[row    ][col + c] == reverse.charAt(c) ? 0 : 1 << 4;
    flags |= board[row + c][col + c] == reverse.charAt(c) ? 0 : 1 << 5;
 }
 if(flags != 0b111111)
     return true;

Just a pity that Java does not support converting boolean to int implicitly here (like e. g. C or C++ do – oh, by the way, does C#?), otherwise we could have written:

flags |= (a == b) << n;

Find word letter grid

2 Answers2