I was just catching up on xkcd, and this showed up:
And wanted to shout from the rooftops that in high school we had a Bendix/Control Data G-15, and I "wrote a tic-tac-toe program," but the program was basically a binary tree - I had worked out the whole game tree longhand, on about 12 sheets, in pencil.
I'm way too lazy to go through xkcd's chart, although I wouldn't be surprised to find that it works - there are only 512 possible games, after all. :-)
Cheers! Rich
More like 39,366 possible games.
Or 362,880 if you play stupidly and don't stop when you win.
Including mirrors and rotations?
Yes. I wrote a program to pre-calculate the best move for every possible game and store them in a database. That's how many entries there are.
I guess my question, hence your answer, was ambiguous. ;-) Is the 39K number
*including* the mirrors and rotations or excluding them, because they really are the same game. +-+-+-+ +-+-+-+ +-+-+-+ |X| | | |X|O| | | | | | +-+-+-+ +-+-+-+ +-+-+-+ |O| | | == | | | | == | | |O| +-+-+-+ +-+-+-+ +-+-+-+ | | | | | | | | | | |X| +-+-+-+ +-+-+-+ +-+-+-+
Thinking more, 9! = 362,880 (10*39K), so...
I mentioned that a few posts ago too.
Well, it was in my case - I just told the computer to play every game, then worked backwards from winning positions to find which moves forced the game to that win. It's not a "big" problem compared to today's computing resources.
The G-15 was neat. Mapping spacing of sequential commands on the drum for maximum speed, finding ways to use the dinky core memory, etc.
OK, I spoke too soon; you don't put all your Xs or Os on the board at once.
I should have said something like, "512 possible outcomes." Heck, not even that, because there's always a maximum of 5 Xs and 4 Os; there are even less ways to arrange them than 512.
But I admit, there are lots of different ways to get to any given pattern, and I'm WAY too lazy to go through all of tem.
Thanks, Rich
But that list would include moves that, in a real game, would be really stupid. (like, don't block when you should, etc.)
Maybe that's why I only came up with 512 - I threw out all of the dumb moves. ;-D
Cheers! Rich
Stupid moves are still moves.
I doubt it. ;-)
The G-15 I used didn't have any core at all - just the rotating drum. There were "short lines," for the accumulator, index registers, and "scratchpad;" is that what you're referring to?
Cheers! Rich
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