Here's a version run through Perltidy - not too hard to understand if you know Perl regular expressions. The $c is the secret, $_ is the guess, and the code depends on matching the guess concatenated with the secret. Interesting code, and not a bad example of Perl really - it's just that the traditional scrunched-up formatting makes it look like line noise. I also made some minor changes for understandability/legibility. Of course, I realise this is entirely against the idea of obfuscated code :) 
#!/usr/bin/perl -l
$c .= 1 + int rand 6 for 1 .. 4;      # Build up the secret

while (<>) {
    /^\d{4}$|!/ || next;              # Check user entered 4 digits

    $_ .= $c;

    1 while s!(.)(.{4})\1!?$2*!s;       # Match in right position

    1 while s!(\d)(.*\n.*)\1!+$2!;      # Match somewhere

    print /[*+]/g;                      # Print matches

    /\*{4}|!/ && exit;
}

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In reply to Re: Re: Re: Mastermind in 2 lines by Anonymous Monk
in thread Mastermind in 2 lines by jsrn

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