G'day supriyoch_2008,
You should take a look at sort. Is there something you don't understand about ascending and descending sorts? This technique worked for me:
$ perl -Mstrict -Mwarnings -E '
my @x = qw/c d e f k l m n/;
my @y = qw/4 6 5 2 9 7 8 3/;
my @sorted_y = sort { $a <=> $b } @y;
my %yx_map = map { $y[$_] => [$x[$_], $_] } 0 .. $#y;
say q{Max values:};
say "$_ = $yx_map{$_}[0] at $yx_map{$_}[1]" for reverse @sorted_y[
+-5..-1];
say q{Min values:};
say "$_ = $yx_map{$_}[0] at $yx_map{$_}[1]" for @sorted_y[0..4];
'
Max values:
9 = k at 4
8 = m at 6
7 = l at 5
6 = d at 1
5 = e at 2
Min values:
2 = f at 3
3 = n at 7
4 = c at 0
5 = e at 2
6 = d at 1