Data commit

Task/Knapsack-problem-Bounded/Ruby/knapsack-problem-bounded.rb

@@ -0,0 +1,59 @@
+# Item struct to represent each item in the problem
+Struct.new('Item', :name, :weight, :value, :count)
+
+$items = [
+  Struct::Item.new('map', 9, 150, 1),
+  Struct::Item.new('compass', 13, 35, 1),
+  Struct::Item.new('water', 153, 200, 3),
+  Struct::Item.new('sandwich', 50, 60, 2),
+  Struct::Item.new('glucose', 15, 60, 2),
+  Struct::Item.new('tin', 68, 45, 3),
+  Struct::Item.new('banana', 27, 60, 3),
+  Struct::Item.new('apple', 39, 40, 3),
+  Struct::Item.new('cheese', 23, 30, 1),
+  Struct::Item.new('beer', 52, 10, 3),
+  Struct::Item.new('suntan cream', 11, 70, 1),
+  Struct::Item.new('camera', 32, 30, 1),
+  Struct::Item.new('t-shirt', 24, 15, 2),
+  Struct::Item.new('trousers', 48, 10, 2),
+  Struct::Item.new('umbrella', 73, 40, 1),
+  Struct::Item.new('w-trousers', 42, 70, 1),
+  Struct::Item.new('w-overcoat', 43, 75, 1),
+  Struct::Item.new('note-case', 22, 80, 1),
+  Struct::Item.new('sunglasses', 7, 20, 1),
+  Struct::Item.new('towel', 18, 12, 2),
+  Struct::Item.new('socks', 4, 50, 1),
+  Struct::Item.new('book', 30, 10, 2)
+]
+
+def choose_item(weight, id, cache)
+  return 0, [] if id < 0
+
+  k = [weight, id]
+  return cache[k] unless cache[k].nil?
+  value = $items[id].value
+  best_v = 0
+  best_list = []
+  ($items[id].count+1).times do |i|
+    wlim = weight - i * $items[id].weight
+    break if wlim < 0
+    val, taken = choose_item(wlim, id - 1, cache)
+    if val + i * value > best_v
+      best_v = val + i * value
+      best_list = taken + [i]
+    end
+  end
+  cache[k] = [best_v, best_list]
+  return [best_v, best_list]
+end
+
+val, list = choose_item(400, $items.length - 1, {})
+w = 0
+list.each_with_index do |cnt, i|
+  if cnt > 0
+    print "#{cnt} #{$items[i].name}\n"
+    w += $items[i][1] * cnt
+  end
+end
+
+p "Total weight: #{w}, Value: #{val}"