#!/usr/bin/perl
use strict;
use warnings;
my @item_array = ([1, 2, 20],
                  [2, 3, 15],
                  [3,4,3],
                  [4, 5, 17],
                  [5,6,28],
                  [6,1,23],
                  [1, 7, 1],
                  [2, 7, 4],
                  [3, 7, 9,],
                  [4, 7, 16],
                  [5, 7, 25],
                  [6, 7, 36],
                  );
my @sorted_array = sort { $a->[2] <=> $b->[2] } @item_array;
for (@sorted_array) {
    print join("\t", @$_), "\n";
}

##</code><code>##

1	7	1
3	4	3
2	7	4
3	7	9
2	3	15
4	7	16
4	5	17
1	2	20
6	1	23
5	7	25
5	6	28
6	7	36