#!/usr/bin/perl

# http://perlmonks.org/?node_id=1169831

use strict;
use warnings;

$_ = <<END;
a 23  11
b 24  15
c 16  19
d 8 2
e 40  41
END
s/ +/\t/g; # replace tabs if pasted out

my @array;

@array[sort {$b <=> $a} /\t(\d+)\t/g] = 1..tr/\n//;
s/\t\K(\d+)(?=\t)/$array[$1]/ge;

@array[sort {$b <=> $a} /\b(\d+)$/gm] = 1..tr/\n//;
s/\b(\d+)$/$array[$1]/gem;

print;