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

my %hash;
my @x = qw/d b c e a f/;
my @y = qw/4 6 5 2 9 1/;

@hash{@x} = @y;

print Dumper \%hash;

my @sorted = (sort {$hash{$b} <=> $hash{$a}} keys %hash) [0 .. 3];

print Dumper \@sorted;

__END__

$ perl test.pl
$VAR1 = {
          'f' => '1',
          'c' => '5',
          'a' => '9',
          'd' => '4',
          'b' => '6',
          'e' => '2'
        };
$VAR1 = [
          'a',
          'b',
          'c',
          'd'
        ];