Re: Which Permute or other module can give me all possible subsets of 6 numbers out of 40?

#!/usr/bin/perl

# http://perlmonks.org/?node_id=1212655

use strict;
use warnings;

my $draw = 2;
my $from = 3;

my $pattern = '(2+?)' x $draw;
(2 x $from) =~ /^$pattern(??{print "@+[1..$draw]\n"})/;
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Comment on Re: Which Permute or other module can give me all possible subsets of 6 numbers out of 40? Download Code

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Re^2: Which Permute or other module can give me all possible subsets of 6 numbers out of 40? by choroba (Cardinal) on Apr 11, 2018 at 11:10 UTC
Excuse my thickness, but why do we need `2` here? It works equally well with 0, 3, 4, etc., or with characters like `a`, `b` etc., but it doesn't work with `1`. Why's that? ($q=q:Sq=~/;[c](.)(.)/;chr(-\|\|-\|5+lengthSq)`"S\|oS2"`map{chr \|+ord }map{substrSq`S_+\|`\|}3E\|-\|`7**2-3:)=~y+S\|`+$1,++print+eval$q,q,a, [download]	[reply] [d/l] [select]
Re^3: Which Permute or other module can give me all possible subsets of 6 numbers out of 40? by tybalt89 (Monsignor) on Apr 11, 2018 at 13:28 UTC
Because the print returns 1, and we need the (??{...}) block to return something that does not match, to cause the regex engine to backtrack.	[reply]
Re^4: Which Permute or other module can give me all possible subsets of 6 numbers out of 40? by choroba (Cardinal) on Apr 11, 2018 at 13:33 UTC
Of course! I was blind. I solved a similar issue years ago, but I used the FAIL as I couldn't choose what characters would be involved. Here, it would be (note that (?{}) is used): `($digit x $from) =~ /^$pattern(?{print "@+[1 .. $draw]\n"})(?!)/;` [download] And it works for `$digit = 1`, too. ($q=q:Sq=~/;[c](.)(.)/;chr(-\|\|-\|5+lengthSq)`"S\|oS2"`map{chr \|+ord }map{substrSq`S_+\|`\|}3E\|-\|`7**2-3:)=~y+S\|`+$1,++print+eval$q,q,a, [download]	[reply] [d/l] [select]