Code for Challenge #59

2 files changed, 89 insertions, 0 deletions

diff --git a/challenge-059/dave-jacoby/perl/ch-1.pl b/challenge-059/dave-jacoby/perl/ch-1.pl
new file mode 100755
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+++ b/challenge-059/dave-jacoby/perl/ch-1.pl
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+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use utf8;
+use feature qw{ postderef say signatures state switch };
+no warnings qw{ experimental };
+
+my $k     = 3;
+my $input = [ 1, 4, 3, 2, 5, 2 ];
+
+say display_ll($input);
+my $output = task_1( $k, $input );
+say display_ll($output);
+
+# the "simple" version, not using actual linked lists
+# but not doing anything you can't regularly due with 
+# singly-linked lists, basically shift/remove-first
+# and push/add-last. Adding the first element of the 
+# second linked list to the end of the first linked 
+# list makes it a longer linked list.
+
+# I think I'll have to make my Node code into an actual
+# linked list eventually
+
+sub task_1 ( $k, $array ) {
+    my $output = [];
+    my @below ;
+    my @above ;
+    while ( $array->@* ) {
+        my $l = shift $array->@*;
+        if ( $l < $k ) {
+            push @below, $l;
+            next;
+        }
+        push @above, $l;
+    }
+    push $output->@*, @below, @above;
+    return $output;
+}
+
+sub display_ll($array) {
+    return join ' -> ', $array->@*;
+}
diff --git a/challenge-059/dave-jacoby/perl/ch-2.pl b/challenge-059/dave-jacoby/perl/ch-2.pl
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index 0000000000..7642c3e7ee
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+++ b/challenge-059/dave-jacoby/perl/ch-2.pl
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+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use utf8;
+use feature qw{ postderef say signatures state switch };
+no warnings qw{ experimental };
+
+use List::Util qw{ sum };
+use Algorithm::Combinatorics 'combinations';
+
+use JSON;
+my $json = JSON->new->canonical->allow_nonref;
+
+say f2();
+say f2(1);
+say f2( 1, 3 );
+say f2( 2, 3, 4 );
+say f2( 2, 3, 4, 5 );
+say f2( 99,101 );
+
+# if array has < 2 entries, return 0 because there's not enough
+# to work with.
+# use combinations to get all possible combinations of n vals
+#   - for example, w/ 1,2,3: [1,2],[1,3],[2,3]
+sub f2 ( @array ) {
+    return 0 if scalar @array < 2;
+    my $sum = 0;
+    for my $combo ( combinations( \@array, 2 ) ) {
+        my $f = f( $combo->@* );
+        $sum += $f;
+    }
+    return $sum;
+}
+
+# back to front:
+#   $i ^ $j - XOR, which is $i or $j but not $i and $j
+#   sprintf - make a string representation of a
+#               binary number of the result
+#   split // - turn '00001111' into [0,0,0,0,1,1,1,1]
+#   sum     - add all the numbers in the array together
+sub f ( $i, $j ) {
+    return sum split //, sprintf '%b', $i ^ $j;
+}
+