A solution to http://blogs.perl.org/users/ovid/2014/12/a-small-puzzle-for-you.html

ovid_puzzle.pl

#!/usr/bin/env perl
#
# A solution to http://blogs.perl.org/users/ovid/2014/12/a-small-puzzle-for-you.html

use Modern::Perl;
use Data::Printer multiline => 0;

my @a = ( 'b', 'c', 'f' );
my @b = ( 'a', 'd' );
my @c = ( 'c', 'd', 'e' );

# build a map of which values appear in each array
my %d;
$d{$a[$_]}{a} = $a[$_] for 0..$#a;
$d{$b[$_]}{b} = $b[$_] for 0..$#b;
$d{$c[$_]}{c} = $c[$_] for 0..$#c;

# populate (overwrite) the arrays with all the values from the original array,
# but in their proper position.
my $n = 0;
for (sort keys %d) {
  $a[$n] = $d{$_}{a};
  $b[$n] = $d{$_}{b};
  $c[$n] = $d{$_}{c};
  $n++;
}

p @a;
p @b;
p @c;