Instructions

Larry is a Lisp Alien that likes to write code to play games. Today they want to write a few functions to help them with a game which is a lot like tic-tac-toe.

Like tic-tac-toe this game is played on a board which is a 3x3 grid.

1. Starting from scratch

First Larry needs a function to make a blank board make-empty-board All the cells of the board should be NIL.

2. Starting from an existing board

Next Larry needs a function to make a board from a list of rows. For example:

3. Winning condition

If there is a case where there are 3 of the same symbol in a row then that player has won. Larry will need a function, all-the-same-p, which given an array of 3 items will evaluate to T if all the items are the same symbol. (eq can be used to determine if two symbols are the same.)

4. In a row

Now Larry needs a way to get the elements of a row. The function row will take a board and a row number and should return an array of the elements in that row.

5. In a column

Finally Larry needs a way to get the elements of a column. The function column will take a board and a column number and should return an array of the elements in that column.