Knapsack problem

1 files changed, 30 insertions, 0 deletions

diff --git a/challenge-036/simon-proctor/perl6/ch-2.p6 b/challenge-036/simon-proctor/perl6/ch-2.p6
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+++ b/challenge-036/simon-proctor/perl6/ch-2.p6
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+#!/usr/bin/env perl6
+
+use v6;
+
+class Box {
+    has Int $.weight;
+    has Int $.worth;
+
+    method gist { "{$!weight}kg worth £{$!worth}" }
+}
+
+#| Calculate the most valuable boxes you can carry
+sub MAIN(
+    Int $max-boxes = 5, #= Max number of boxes you can carry (default 5)
+    Int $max-weight = 15, #= Max weight of boxes you can carry (default 15kg)
+) {
+    my @boxes = ( Box.new( :1weight, :1worth ),
+                  Box.new( :1weight, :2worth ),
+                  Box.new( :2weight, :2worth ),
+                  Box.new( :12weight, :4worth ),
+                  Box.new( :4weight, :10worth ) );
+
+    say "I can take up to {$max-boxes} boxes weighing up to {$max-weight}kg from this selection";
+    .say for @boxes;
+
+    my @options = @boxes.combinations().grep( *.elems <= $max-boxes ).grep( { ([+] $_.map( *.weight )) <= $max-weight } ).sort( { ( [+] $^b.map( *.worth ) ) cmp ( [+] $^a.map( *.worth ) ) } );
+
+    say "I think I'll take :";
+    .say for @options[0].list;
+}