Re: (Golf) Tic Tac Toe

[ambrus]

in reply to (Golf) Tic Tac Toe

Just an idea. This may or may not help in the golf, but is good to know anyway.

If you take this magic square:

2 9 4
7 5 3
6 1 8

and play tic-tac-toe on it, you have three in a row iff you have three different cells so that the sum of their three numbers is 15.

Source of the idea:

Csákány Béla, Diszkrét matematikai játékok.
1998, Polygon, Szeged
pp. 100-101

Update: changed 1 in 1st row to 2. Thanks to jdhawke and also QM for noticing the typo.

Update: this one does not check for valid moves so it's easy to cheat. Also, it does not detect ties yet.

s;;294
753
618
;;$f=(OX)x9;{print$_,$u=chop$f;$n=<>-Q;s;$n;$u;e;$$u&1<<15-$n&&die$u.$
+/;$$u|=$$u[0]<<$n;$$u[0]|=1<<$n;redo}

[jdhawke]

should that square be:


2 9 4
7 5 3
6 1 8

Otherwise the first column and row only sums to 14. --JDHawke

[QM]

You have a typo I think:

1 9 4
7 5 3
6 1 8

1st column and major diagonal do not add to 15.

[thospel]

Run this with an odd argument (like 3) to get a magic square :-)

print"@{$_=++$_%@F+$p--%@F*@F+1for@F,$p;F}
"for@F=0..~-pop