langs a-z

Task/Knapsack-problem-Continuous/Perl-6/knapsack-problem-continuous.pl6

@@ -0,0 +1,44 @@
+class KnapsackItem {
+  has $.name;
+  has $.weight is rw;
+  has $.price is rw;
+  has $.ppw;
+
+  method new (Str $n, $w, $p) {
+    KnapsackItem.bless(*, :name($n), :weight($w), :price($p), :ppw($w/$p))
+  }
+
+  method cut-maybe ($max-weight) {
+    return False if $max-weight > $.weight;
+    $.price = $max-weight / $.ppw;
+    $.weight = $.ppw * $.price;
+    return True;
+  }
+
+  method Str () { sprintf "%8s %1.2f   %3.2f",
+                           $.name,
+                               $.weight,
+                                       $.price }
+}
+
+my $max-w = 15;
+say    "Item    Portion Value";
+
+.say for gather
+    for < beef    3.8 36
+          pork    5.4 43
+          ham     3.6 90
+          greaves 2.4 45
+          flitch  4.0 30
+          brawn   2.5 56
+          welt    3.7 67
+          salami  3.0 95
+          sausage 5.9 98 >
+        ==> map { KnapsackItem.new($^a, $^b, $^c) }
+        ==> sort *.ppw
+    {
+        my $last-one = .cut-maybe($max-w);
+        take $_;
+        $max-w -= .weight;
+        last if $last-one;
+    }