# GeekDad Puzzle of the Week – Stick Stac Toe

This past weekend, our family visited a friendly family’s rural farm property for some rest and relaxation. The kids got to run, try archery, swing, and generally just be kids. For part of the weekend, two of the girls set up a “tic tac toe” grid with sticks, and then dropped rocks onto it to place their Xs and Os.

If the placement of each new X and O rock is random for each of the unpopulated sections, and we assume that the grid is set up such that occupied sections of the grid don’t accept new stones, is there an advantage to placing the first rock? Additionally, if try to “aim” your stone for the center square (assuming it is unoccupied) and this double your odds of capturing it, what does this do to your chance of winning if you went first? What if you went second and aimed?

As always, please drop your solutions in an email to GeekDad Central. All correct (or reasonably correct) solutions will be entered into a random drawing. Many thanks to ThinkGeek for providing our puzzle prize, a \$50 ThinkGeek gift certificate.

Good luck, and happy puzzling!