void init(void)
{
    {
        n = d * d - 1;
        blank_tile = n;
        for (int i = 0; i < d; i++){
            for (int j = 0; j < d; j++) {
                board[i][j] = n;
                n--;
            }
        }

        n = blank_tile;

        // switches the last two tiles if the board is of an odd dimension
        if ((d % 2) != 0) {
            int temp = board[d][d-1];
            board[d][d-1] = board[d][d-2];
            board[d][d-2] = temp;
        }
    }
}

/**
 * Prints the board in its current state.
 */
void draw(void)
{
    int current = 0;
    for (int i = 0; i < d; i++){
        for (int j = 0; j < d; j++) {
            // prints the underscore or blank tile
            if (current == blank_tile){
                printf("|_|");
            } else {
                printf("|%d|", board[i][j]);
            }
            current++;
        }
        printf("\n");
    }
}

/**
 * If tile borders empty space, moves tile and returns true, else
 * returns false.
 */
bool move(int tile)
{
    int temp = n - tile + 1;
    tile = temp;

    if (tile < 0 || tile > n)
        return false;
    //printf("Value: %d\n", tile);

    if (((tile % d) != 0 && (tile - 1) == blank_tile) || // checks to the left and makes sure that it it is not up against left edge
    ((tile % d) != (d-1) && (tile + 1) == blank_tile) ||    // makes sure that  it is not up against right edge and checks to the right
    (tile - d) == blank_tile ||     // checks upward
    (tile + d) == blank_tile)  {    // checks downward
        int blank_row = blank_tile / d;
        int blank_col = blank_tile % d;
        int tile_row = tile / d;
        int tile_col = tile % d;
        board[blank_row][blank_col] = board[tile_row][tile_col];
        blank_tile = tile;
        return true;
    }
    return false;
}

/**
 * Returns true if game is won (i.e., board is in winning configuration),
 * else false.
 */
bool won(void)
{
    int current_tile = -1;
    for (int i = 0; i < d; i++){
        for (int j = 0; j < d; j++) {
            if (board[i][j] > current_tile) {
                current_tile = board[i][j];
            } else {
                return false;
            }
        }
    }
    return true;
}