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Re^2: Generate all unique combinations of 1 and 0 using specified length of "0"-string and count of 1's

by LanX (Sage)
on Sep 19, 2020 at 15:38 UTC ( #11121947=note: print w/replies, xml ) Need Help??


in reply to Re: Generate all unique combinations of 1 and 0 using specified length of "0"-string and count of 1's
in thread Generate all unique combinations of 1 and 0 using specified length of "0"-string and count of 1's

> so you need recursion (or fake it).

so here a recursive version with global variables (because I also wanted to provide a solution with two nested loops "faking" recursion, but gave up)

NB: it's optimized for the dual case, where it's easier to set 0s into a string full of 1s.

use 5.12.0; use strict; use warnings; use Data::Dump qw/pp dd/; use Test::More; my $ones = 3; my $len = 5; my @res; my ($zero,$one) = ('0','1'); # optimize dual case if ($ones > $len/2) { ($zero,$one) = ($one,$zero); $ones = $len-$ones; } my $max = $len - 1; our $str = $zero x $len; our $level = 0; rec(0); pp \@res; sub rec { local $level = $level + 1; my ($start) =@_; for my $idx ( $start .. $max ) { local $str = $str; substr $str, $idx, 1, $one; if ($level < $ones) { rec( $idx + 1 ); } else { push @res, $str; } } }

[ "00111", "01011", "01101", "01110", 10011, 10101, 10110, 11001, 11010, 11100, ]

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

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