#!/usr/bin/perl
	
	# https://www.perlmonks.org/?node_id=1226058
	
	use warnings;
	use re 'eval';
	
	$\ = $/;
	
	for my $tc (
		[ 'abc', 1 ],
		[ 'abc', 2 ],
		[ 'abc', 3 ],
		){
		
		my( $string, $times ) = @{ $tc };
		
		$_ = ( ',' . reverse $string ) x ( $times * length $string );
		
		print;
		
		my @permutations;
		
		my %occ;
		
		my $re = 
			', \w*(\w)\w* 
			(?:
				(?{ $occ{ $^N } ++ })
				|
				(?{ $occ{ $^N } -- }) 
				(*F)
			)
			' x ( $times * length $string );
			;
		
		/
			$re
			$
			(??{ ( grep $_ != $times, values %occ ) ? '(*F)' : '' })
			(?{ push @permutations, 
				join '', 
				grep length, 
				$1, $2, $3, 
				$4, $5, $6, 
				$7, $8, $9, 
				})
			(*F)
		/x;

		print for 
			@permutations, 
			~~ @permutations
			;
		
		}
	

##</code><code>##

#!/usr/bin/perl
	
	# https://www.perlmonks.org/?node_id=1226058
	
	use warnings;
	use re 'eval';
	
	$\ = $/;
	
	for my $tc (
		[ 'abc', 1 ],
		[ 'abc', 2 ],
		[ 'abc', 3 ],
		){
		
		my( $string, $times ) = @{ $tc };
		
		$_ = ( ',' . reverse $string ) x ( $times * length $string );
		
		print;
		
		my @permutations;
		
		my %occ;
		
		my $current = '';
		
		my $re = 
			', \w*(\w)\w* 
			(?:
				(?{ $occ{ $^N } ++ })
				(?{ $current .= $^N })
				|
				(?{ $occ{ $^N } -- }) 
				(?{ chop $current })
				(*F)
			)
			' x ( $times * length $string );
			;
		
		/
			$re
			$
			(??{ ( grep $_ != $times, values %occ ) ? '(*F)' : '' })
			(?{ push @permutations, 
				$current,
				})
			(*F)
		/x;

		print for 
			@permutations, 
			~~ @permutations,
			;
		
		}
	
	

##</code><code>##

		my $re = 
			', \w*(\w)\w* 
			(?:
				(?{ $occ{ $^N } ++ })
				|
				(?{ $occ{ $^N } -- }) 
				(*F)
			)
			(??{ ( grep $_ > $times, values %occ ) ? "(*F)" : "" })
			' x ( $times * length $string );
			;