Our Combination code in Perl.
Combination Class File:
package COMBINATION;
BEGIN {
require Exporter;
# for the sake of standard
our $VERSION = 2017.10;
# Inherit from exporter to export functions and variables
our @ISA = qw(Exporter);
# Functions and variables to be exported by default
our @EXPORT_OK = qw(possibleWordCombinations);
}
use warnings;
use strict;
my @words;
my $r; # min length of word
my @comb_store; # array of references
my $i;
# simulate an object construct
sub new {
my $self = shift;
my $this = {};
bless $this, $self;
return $this;
}
# point of entry
# returns an array reference of references to array strings
sub possibleWordCombinations {
shift;
my $arg = shift;
@words = @{$arg};
$r = shift;
@comb_store = ();
$i = 0;
# check for conformity
if ($r <= 0 || $r > scalar @words) {
@comb_store = ();
} elsif ($r == 1) {
$comb_store[$_] = [$words[$_]] for (0 .. $#words);
} else {
progressiveCombination();
}
return \@comb_store;
}
# do combinations for all 'words' element
sub progressiveCombination {
# anonymous reference to a single element array as 1st argument
repetitivePairing([$words[$i]], $i + 1);
if ($i + $r <= scalar @words) {
# move on to next degree
$i++;
progressiveCombination();
}
}
# do all possible combinations for 1st element of this array
sub repetitivePairing {
my $prefix_word = shift; # array reference
my $position = shift; # int
my @auxiliary_store = ();
for (0 .. ($#words - $position)) {
# check if desired -- r -- size will be realised
if ($r - scalar @{$prefix_word} <= scalar @words - $position) {
# dereference 'prefix_word' and save it as an anonymous array reference
$auxiliary_store[$_] = [@{$prefix_word}];
# save current 'word' to what 'aux_store[$_]' is referencing
push @{$auxiliary_store[$_]}, $words[$position];
if (scalar @{$auxiliary_store[$_]} < $r) {
# 1st argument is an array reference - add next word on
repetitivePairing($auxiliary_store[$_], $position + 1);
} else {
# save a reference '$auxiliary_store[$_]' to '@comb_store'
push(@comb_store, $auxiliary_store[$_]);
}
}
$position++;
}
}
1;Main Class:
#!/usr/bin/perl;
use strict;
use warnings;
use COMBINATION;
my @subjects = ("Eno", "Chidi", "Olu", "Ahmed", "Osas", "Gbeda");
my $r = 3;
# Use the combination module/class
my $combo = COMBINATION->new();
# $result receives an array reference of references
my $result = $combo->possibleWordCombinations(\@subjects, $r);
print ("[", join(", ", @subjects), "] combination ", $r, ":\n\n");
# for each array reference in a dereferenced '$result'
my $i = 0;
print (++$i, ": ", join(", ", @{$_}), "\n") for @{$result};
print ("\n\nNumber of ways is ", scalar @{$result}, ".");
print "\n\n";Try it out!
Elegance (0.0)
