1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
|
#! /opt/local/bin/perl
#
# number_combo_convo.pl
#
# TASK #1 › Number Combinations
# Submitted by: Mohammad S Anwar
#
# You are given two integers $max and $elems. Write a script print all
# possible combinations of $elems numbers from the list 1 2 3 … $max.
#
# Every combination should be sorted i.e. [2,3] is valid
# combination but [3,2] is not.
#
# Example:
# Input: $max = 5, $elems = 2
#
# Output: [ [1,2], [1,3], [1,4], [1,5], [2,3], [2,4], [2,5], [3,4], [3,5], [4,5] ]
#
#
# 2020 colin crain
## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ##
use warnings;
use strict;
use feature ":5.26";
## ## ## ## ## MAIN:
my ($max, $elems) = @ARGV;
($elems > $max or @ARGV < 2) and do {
say "Usage: ./number_combos.pl max elements
max cannot be less than # of elements";
exit };
my @list = add_elements( $max, $elems, [[]] )->@*;
say ( "[" . (join ', ', map { "[". (join ',', $_->@*) . "]" } @list) . "]");
## ## ## ## ## SUBS:
sub add_elements {
my ($max, $elems, $list) = @_;
return $list if $list->[0]->@* == $elems;
my @newlist = ();
my $pos = $list->[0]->@* + 1; ## this position, elems of prev list + 1
for my $combo ( $list->@* ) {
my $prev = $combo->[-1] // 0;
my $start = $prev + 1; ## value of last elem in list + 1
my $end = $max - $elems + $pos; ## max - length + position
for ($start .. $end ) {
push @newlist, [ $combo->@*, $_ ]
}
}
return add_elements( $max, $elems, \@newlist);
}
|
