Question

I realize this code might be a bit dense to read, what I´ve tried to do is to adapt a standard recursive maze-solving algorithm – where all directions are tried until a solution is found, to an algorithm for the game ‘boggle’ that checks if the target word can formed on the grid by going in either of the four directions. I realize this code got more than one bug, but I´d like some input on how to solve the most important like that the direction and way it is searching the grid is obviously not working.

Console output:

Enter word: 
aefn
First matching letter found at [row: 0] [col: 0]
findNext: Point location: Y[0] X[0]

Point location: Y[0] X[-1]
A //(This is the algorithm trying to find "targetWord" on grid "currentWord")
Point location: Y[1] X[0]
AA
Point location: Y[0] X[0]
AAE
Point location: Y[0] X[-1]
AAEA
Point location: Y[1] X[0]
AAEAA
Point location: Y[0] X[1]
AAEAAA
Point location: Y[-1] X[0]
AAEAAAA
Point location: Y[1] X[1]
AAEE
Point location: Y[1] X[0]
AAEEU
Point location: Y[2] X[1]
AAEEUU
Point location: Y[1] X[2]
AAEEUUU
Point location: Y[0] X[1]
AAEEUUUU
Point location: Y[0] X[2]
AAEEE
Point location: Y[-1] X[1]
AAEEEE
Point location: Y[0] X[1]
AAA
Point location: Y[1] X[-1]
AAAE
Point location: Y[2] X[0]
AAAEE
Point location: Y[1] X[1]
AAAEEE
Point location: Y[0] X[0]
AAAEEEE
Point location: Y[-1] X[0]
AAAA

Code:

enum Direction { NORTH,
                 EAST,
                 SOUTH,
                 WEST };






/**  Attempts to find a matching letter on the grid to the first letter in the 
  *  targetWord, if found it stores it location in grid in 'point' and calls
  *  findNext() with the location of matching letter stored in the 'point'.  
  */
bool findMatchingFirstLetter(Grid<char> &cubeGrid, string currentWord, string targetWord, int index)
{

    for (int row = 0; row < cubeGrid.numRows(); row++)
    {
        for (int col = 0; col < cubeGrid.numCols(); col++)
        {
            if (cubeGrid.get(row, col ) == targetWord[0])
            {
                cout <<  "First matching letter found at [row: " << row << "] [col: " << col << "]" << endl;
                GPoint point(col, row);
                cout << "findNext: " << findNextRecur(cubeGrid, currentWord, targetWord, index, point) << endl;

            }
        }
    }
    return false;
}



/**  Recursive function.
  *  Exhaustively searches the grid for all possible combinations, moving in all 
  *  compass directions. */
bool findNextRecur(Grid<char> &cubeGrid, string currentWord, string targetWord, int index, GPoint point)
{
    cout << "Point location: Y[" << point.getY() << "] X[" << point.getX() << "]" << endl;
    cout << currentWord << endl;
    if (currentWord == targetWord)
        return true;
    if (currentWord.length() > targetWord.length() || 
        point.getX() > cubeGrid.numCols() ||
        point.getX() < 0 ||
        point.getY() > cubeGrid.numRows() ||
        point.getY() < 0)
    { return false; }


    for (Direction dir = NORTH; dir <= WEST; dir++ )
    {

        if (findNextRecur(cubeGrid,
                          currentWord += cubeGrid.get(point.getY(), point.getX()),
                          targetWord,
                          index,    //index is currently not in use.
                          adjacentPoint(point, dir)))
        { return true; }
    }
}



GPoint adjacentPoint(GPoint point, Direction dir)
{
    switch  (dir) {
        case NORTH: return GPoint(point.getY()-1, point.getX());
        case EAST: return GPoint(point.getY(), point.getX()+1);
        case SOUTH: return GPoint(point.getY()+1, point.getX());
        case WEST: return GPoint(point.getY(), point.getX()-1);
    }
    return point;
}


/**  Wrapper 
  */
bool findWordOnGrid(Grid<char> &cubeGrid, string word)
{
    cout << findMatchingFirstLetter(cubeGrid, "", toUpperCase(word), 0) << endl;
    return true;
}

Answer 1

Not sure if this the only problem, but currentWord += ... should only be currentWord + .... The += is changing the local currentWord variable as each of the 4 directions are probed, rather than simply passing the new currentWord into the recursive function.