Code Golf: Tic Tac Toe

Answer 1

I'm sure there's a shorter way to do this but... Perl, 141 characters (134 inside the function)

sub t{$r=0;@b=@_;@w=map{[split//]}split/,/,"012,345,678,036,147,258,048,246";for(@w){@z=map{$b[$_]}@$_;$r=$z[0]if!grep{!$_||$_!=$z[0]}@z;}$r;}

Answer 2

C, 99 chars

Not a winner, but maybe there's room for improvement. Never did this before. Original concept, first draft.

#define l w|=*b&b[s]&b[2*s];b+=3/s;s
f(int*b){int s=4,w=0;l=3;l;l;l=2;--b;l=1;b-=3;l;l;return l;}

Thanks to KennyTM for a few ideas and the test harness.

The "development version":

#define l w|=*b&b[s]&b[2*s];b+=3/s;s // check one possible win
f( int *b ) {
        int s=4,w=0; // s = stride, w = winner
        l=3;     // check stride 4 and set to 3
        l;l;l=2; // check stride 3, set to 2
        --b;l=1; // check stride 2, set to 1
        b-=3;l;l; return l; // check stride 1
}

Answer 3

Python, 285 bytes

b,p,q,r=["."]*9,"1","2",range
while"."in b:
 w=[b[i*3:i*3+3]for i in r(3)]+[b[i::3]for i in r(3)]+[b[::4],b[2:8:2]]
 for i in w[:3]:print i
 if["o"]*3 in w or["x"]*3 in w:exit(q)
 while 1:
  m=map(lambda x:x%3-x+x%3+7,r(9)).index(input())
  if"."==b[m]:b[m]=".xo"[int(p)];p,q=q,p;break

...Oh, this wasn't what you meant when you said "Code Golf: Tic Tac Toe"? ;) (enter numpad numbers to place x's or o's, i.e. 7 is north-west)

Long Version

board = ["."]*9   # the board
currentname = "1" # the current player
othername = "2"   # the other player

numpad_dict = {7:0, 8:1, 9:2, # the lambda function really does this!
               4:3, 5:4, 6:5,
               1:6, 2:7, 3:8}

while "." in board:
    # Create an array of possible wins: horizontal, vertical, diagonal
    wins = [board[i*3:i*3+3] for i in range(3)] + \ # horizontal
           [board[i::3]      for i in range(3)] + \ # vertical
           [board[::4], board[2:8:2]]               # diagonal

    for i in wins[:3]: # wins contains the horizontals first,
        print i        # so we use it to print the current board

    if ["o"]*3 in wins or ["x"]*3 in wins: # somebody won!
        exit(othername)                    # print the name of the winner
                                           # (we changed player), and exit
    while True: # wait for the player to make a valid move
        position = numpad_dict[input()] 
        if board[position] == ".": # still empty -> change board
            if currentname == "1":
                board[position] = "x"
            else:
                board[position] = "o"
            currentname, othername = othername, currentname # swap values

Answer 4

J, 97 characters.

1+1 i.~,+./"2>>(0 4 8,2 4 6,(],|:)3 3$i.9)&(e.~)&.>&.>(]<@:#"1~[:#:[:i.2^#)&.>(I.@(1&=);I.@(2&=))

I was planning to post an explanation of how this works, but that was yesterday and now I can't read this code.

The idea is we create a list of all possible winning triples (048,246,012,345,678,036,147,258), then make the powerset of the squares each player has and then intersect the two lists. If there's a match, that's the winner.

Answer 5

Python - 75 chars (64)

I came up with 2 expressions, each 64chars:

max(a[c/8]&a[c/8+c%8]&a[c/8-c%8]for c in map(ord,'\t\33$#"!+9'))

and

max(a[c/5]&a[c/5+c%5]&a[c/5+c%5*2]for c in[1,3,4,8,12,13,16,31])

When you add "W=lambda b:" to make it a function, that makes 75chars. Shortest Python so far?

Answer 6

C# Solution.

Multiply the values in each row, col & diagonal. If result == 1, X wins. If result == 8, O wins.

int v(int[] b)
{
    var i = new[] { new[]{0,1,2}, new[]{3,4,5}, new[]{6,7,8}, new[]{0,3,6}, new[]{1,4,7}, new[]{2,5,8}, new[]{0,4,8}, new[]{2,4,6} };
    foreach(var a in i)
    {
        var n = b[a[0]] * b[a[1]] * b[a[2]];
        if(n==1) return 1;
        if(n==8) return 2;
    }
    return 0;
}