Ann and Beth play tic tac toe with a variation, if you get three in a row, you LOSE and everyone plays with only X (not X and O). If both players play optimally, and Ann goes first, then who will win?
If there's a simple way to do this, I didn't find it. Basically I had to draw out every board position to find which are W or L. (There are 42 board positions with no three-in-a-row, not counting reflections/rotations.)
The only way for Ann to win is to play first in the center square.
Board after Play 1:
Either Play 2 is countered by Play 3 which can bring the board to:
There are four possible Play 4 but Play 5 can always bring the board to:
The 6th play will create three-in-a-row.
Edited on July 23, 2019, 11:12 am
Posted by Jer
on 2019-07-23 11:09:32