#!/usr/bin/perl -w
use strict;
use Data::Dumper;

my %hoa1 = (
             'key1' => ["A","B","C","D"],
             'key2' => ["A","C","D","B"],
             'key3' => ["C","A","D","H"],
             'key4' => ["A","B","I","C"],
         );

my %hoa2 = (
             'key1' => ["A","D"],
             'key2' => ["A","B"],
             'key3' => ["C","H"],
         );

my @answ = align_array(%hoa1);
print Dumper \@answ;

sub align_array
{
    my %hoa = @_;
    my @AoA;
    my @keys = sort keys %hoa;

    foreach my $id ( -1 .. $#keys-1  )
    {

       for  ( 0 .. $#{$hoa{$keys[$id]}}  )
       {
           #Here I get point No.2 done
           $AoA[$_][0] = $hoa{$keys[0]}[$_];

           # I'm totally stuck here, in attempt to do point No.3 to 7
           # How can I evaluate elements of array of varying size
           # dynamically?
          
           if ( $AoA[$_][0] =  $hoa{$keys[$id+1]}[$_] )
           {
               $AoA[$_][$_+2] = $hoa{$keys[$id+1]}[$_];
           }
           elsif ( $AoA[$_][0] =  $hoa{$keys[$id+3]}[$_] )
           {
            $AoA[$_][$_+2] = $hoa{$keys[$id+3]}[$_];
           }
           else
           {
               $AoA[$_+1][$_+2] = "-";
           }

      }

    }                               # -----  end foreach  -----

        return @AoA ;
}