Okay, I have a regular expression for removing duplicate words. The requirements are such that, words can be split up by one or more literal space " " or newline "\n". Now any word that has been seen before, regardless of which line it was on, should not be printed. Here's what I have:
while (<stdin>){
    print map((s;$; ; && $_), grep(!$a{$_}++, split m;\s;,$_));
    print "\n";
}

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Now I know that there may be better ways, so I'd love to see how people can improve on this (mainly so that I learn the secrets of perl, as I always do when I ask a q.) Also note, it would be nice if there's a way to be just as fast, but less memory intensive, as the hash may end up holding as many as 4 million items, with keys of length 1 to 32.

In reply to Removing repeated words by abitkin

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