140 add ch-2.pl

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diff --git a/challenge-140/jake/perl/ch-2.pl b/challenge-140/jake/perl/ch-2.pl
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+#!/r/bin/perl
+
+use strict;
+use warnings;
+use feature 'say';
+
+###
+# You are given 3 positive integers, $i, $j and $k.
+# 
+# Write a script to print the $kth element in the sorted multiplication table of $i and $j.
+# 
+# https://theweeklychallenge.org/blog/perl-weekly-challenge-140/#TASK2
+###
+
+# get input
+print "height: ";
+my $height = <STDIN>;
+print "width: ";
+my $width = <STDIN>;
+print "element to display: ";
+my $element = <STDIN>;
+chomp ( $height, $width, $element );
+
+# sort multiplication table
+my @sorted = sort { $a <=> $b } @{aggregate_multiplication_table ( $height, $width )};
+
+# output desired element
+say ( $sorted[$element - 1] );
+
+# container sub so main needs to pass only 2 arguments
+sub aggregate_multiplication_table {
+    my ( $height, $width ) = @_;
+    _aggregate_multiplication_table ( $height, $width, 1 );
+}
+
+sub _aggregate_multiplication_table {
+    my ( $vertical_range, $horizontal_range, $height_increment, $horizontal_values, $all_values ) = @_;
+
+    # access lists from references
+    my @horizontal_values = @{$horizontal_values // []};
+    my @all_values = @{$all_values // []};
+
+    # once all lines of the table have been written we can return @all_values
+    return \@all_values if $height_increment > $vertical_range;
+
+    # we 'write' the first line of the multiplication table.
+    # after that we run over each value in this first adding each new value to the accumulator @all_values.
+    # we will repeat this for every line that needs to be added to the table.
+    @horizontal_values = 1 ... $horizontal_range;
+    foreach ( @horizontal_values ) {
+        push @all_values, $_ * $height_increment;
+    }
+
+    # we need to increase our line counter upon iteration.
+    # this is necessary for our foreach loop to add the next line in the following iteration.
+    return _aggregate_multiplication_table ( $vertical_range, $horizontal_range, $height_increment + 1, \@horizontal_values, \@all_values );
+}
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