Instructions: When the green flag is clicked a 5 x 5 random arrangement of white and black cards is generated followed by an extra row and column to ensure even parity. Click on any card and the magicians will tell you the row and column you clicked on. Documentation: The Grid sprite generates the random matrix of cards and then sends the message "add-parity" to the Point sprite which adds even parity cards to the right and below the grid. It does this by moving the sprite to each square and checking if it is touching the color black or not; a message "stamp-square" is sent the grid sprite to actually stamp the card. The message "toggle-square" initiates another script which waits for the user to click on a card. The message "stamp-square" changes the color of the card and sends "find-square" to initiate a script to compute the row and column that were changed by traversing each row and column of the matrix and checking if the parity is now odd. If so, an appropriate message is send to one of the magicians. Variables: "row" and "columns" are both set to 5 and can be changed for other sizes; "r", "c" and "n" are used are parameters for the "stamp-square" message to communicate to grid sprite the location and color of the card to stamp; "r" and "c" also communicate to the magicians the row and column to say.
