Fifteen.C Move Function Fails One Check50 Test

Question

I've been working on fifteen.c for a little bit now. Move works just fine except it fails on one of the check50 tests - move up-up-left-down-down-left-up-up-right-down-down-right test. Is there an issue with how I am checking the moves?

Thanks in advance.

Here is my code:

if ( tile == 0 )
{
    return false;
}
for ( int row = 0; row < d; row++ )
{
    for ( int column = 0; column < d; column++ )
    {
        if ( board[row][column] == tile )
        {
            if ( board[row - 1][column] == 0 && row - 1 > 0 )
            {
                board[row - 1][column] = tile;
                board[row][column] = 0;
                return true;
            }
            else if ( board[row + 1][column] == 0 && row + 1 < d )
            {
                board[row + 1][column] = tile;
                board[row][column] = 0;
                return true;
            }
            else if ( board[row][column - 1] == 0 && column - 1 > 0 )
            {
                board[row][column - 1] = tile;
                board[row][column] = 0;
                return true;
            }
            else if ( board[row][column + 1] == 0 && column + 1 < d )
            {
                board[row][column + 1] = tile;
                board[row][column] = 0;
                return true;
            }
        }
    }
}
return false;

Answer 1

Look at the following:

if ( board[row - 1][column] == 0 && row - 1 > 0 )

Why does row-1 have to be greater than 0? 0 is still valid.

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