Code Golf: Tic Tac Toe

Answer 1

Perl, 87 85 characters

A function that returns 0, 1 or 2, using a regular expression, of course (the newline's only there to avoid the scrollbar):

sub V{$"='';$x='(1|2)';"@_"=~
/^(...)*$x\2\2|^..$x.\3.\3|$x..\4..\4|$x...\5...\5/?$^N:0}

It can be called as V(@b), for example.

Answer 2

Perl, 76 char

sub W{$n=$u=0;map{$n++;$u|=$_[$_-$n]&$_[$_]&$_[$_+$n]for/./g}147,4,345,4;$u}

There are three ways to win horizontally:

0,1,2   ==>   1-1, 1, 1+1
3,4,5   ==>   4-1, 4, 4+1
6,7,8   ==>   7-1, 7, 7+1

One way to win diagonally from lower left to upper right:

2,4,6   ==>   4-2, 4, 4+2

Three ways to win vertically:

0,3,6   ==>   3-3, 3, 3+3
1,4,7   ==>   4-3, 4, 4+3
2,5,8   ==>   5-3, 5, 5+3

One way to win diagonally from upper left to lower right:

0,4,8   ==>   4-4, 4, 4+4

Read the middle columns to get the magic numbers.

Answer 3

C#, 154 163 170 177 characters

Borrowing a couple of techniques from other submissions. (didn't know C# let you init arrays like that)

static int V(int[] b)
{
   int[] a={0,1,3,1,6,1,0,3,1,3,2,3,0,4,2,2};
   int r=0,i=-2;
   while((i+=2)<16&&(r|=b[a[i]]&b[a[i]+a[i+1]]&b[a[i]+a[i+1]*2])==0){}
   return r;
}

Answer 4

Visual Basic 275 254 (with loose typing) characters

 Function W(ByVal b())

    Dim r

    For p = 1 To 2

            If b(0) = b(1) = b(2) = p Then r = p
            If b(3) = b(4) = b(5) = p Then r = p
            If b(6) = b(7) = b(8) = p Then r = p
            If b(0) = b(3) = b(6) = p Then r = p
            If b(1) = b(4) = b(7) = p Then r = p
            If b(2) = b(5) = b(8) = p Then r = p
            If b(0) = b(4) = b(8) = p Then r = p
            If b(6) = b(4) = b(2) = p Then r = p

    Next

    Return r

End Function

Answer 5

Python 80 (69) char

Not the shortest Python solution, but I like how it introduces "DICE" into a game of tic-tac-toe:

W=lambda b:max([b[c/5-9]&b[c/5+c%5-9]&b[c/5-c%5-9]for c in map(ord,"DICE>3BQ")])

69 chars for the simpler expression:

max([b[c/5-9]&b[c/5+c%5-9]&b[c/5-c%5-9]for c in map(ord,"DICE>3BQ")])

Answer 6

Ruby, 85 char

def X(b)
u=0
[2,6,7,8,9,13,21,-9].each do|c|u|=b[n=c/5+3]&b[n+c%5]&b[n-c%5]end
u
end

If the input has both players winning, e.g.

     X | O | X
    ---+---+---
     X | O | O
    ---+---+---
     X | O | X

then the output is 3.