Data commit

Task/Knapsack-problem-0-1/Ruby/knapsack-problem-0-1-1.rb

@@ -0,0 +1,43 @@
+KnapsackItem = Struct.new(:name, :weight, :value)
+potential_items = [
+  KnapsackItem['map', 9, 150],              KnapsackItem['compass', 13, 35],
+  KnapsackItem['water', 153, 200],          KnapsackItem['sandwich', 50, 160],
+  KnapsackItem['glucose', 15, 60],          KnapsackItem['tin', 68, 45],
+  KnapsackItem['banana', 27, 60],           KnapsackItem['apple', 39, 40],
+  KnapsackItem['cheese', 23, 30],           KnapsackItem['beer', 52, 10],
+  KnapsackItem['suntan cream', 11, 70],     KnapsackItem['camera', 32, 30],
+  KnapsackItem['t-shirt', 24, 15],          KnapsackItem['trousers', 48, 10],
+  KnapsackItem['umbrella', 73, 40],         KnapsackItem['waterproof trousers', 42, 70],
+  KnapsackItem['waterproof overclothes', 43, 75], KnapsackItem['note-case', 22, 80],
+  KnapsackItem['sunglasses', 7, 20],        KnapsackItem['towel', 18, 12],
+  KnapsackItem['socks', 4, 50],             KnapsackItem['book', 30, 10],
+]
+knapsack_capacity = 400
+
+class Array
+  # do something for each element of the array's power set
+  def power_set
+    yield [] if block_given?
+    self.inject([[]]) do |ps, elem|
+      ps.each_with_object([]) do |i,r|
+        r << i
+        new_subset = i + [elem]
+        yield new_subset if block_given?
+        r << new_subset
+      end
+    end
+  end
+end
+
+maxval, solutions = potential_items.power_set.group_by {|subset|
+  weight = subset.inject(0) {|w, elem| w + elem.weight}
+  weight>knapsack_capacity ? 0 : subset.inject(0){|v, elem| v + elem.value}
+}.max
+
+puts "value: #{maxval}"
+solutions.each do |set|
+  wt, items = 0, []
+  set.each {|elem| wt += elem.weight; items << elem.name}
+  puts "weight: #{wt}"
+  puts "items: #{items.join(',')}"
+end

Task/Knapsack-problem-0-1/Ruby/knapsack-problem-0-1-2.rb

@@ -0,0 +1,63 @@
+KnapsackItem = Struct.new(:name, :weight, :value)
+
+def dynamic_programming_knapsack(items, max_weight)
+  num_items = items.size
+  cost_matrix = Array.new(num_items){Array.new(max_weight+1, 0)}
+
+  num_items.times do |i|
+    (max_weight + 1).times do |j|
+      if(items[i].weight > j)
+        cost_matrix[i][j] = cost_matrix[i-1][j]
+      else
+        cost_matrix[i][j] = [cost_matrix[i-1][j], items[i].value + cost_matrix[i-1][j-items[i].weight]].max
+      end
+    end
+  end
+  used_items = get_used_items(items, cost_matrix)
+  [get_list_of_used_items_names(items, used_items),                     # used items names
+   items.zip(used_items).map{|item,used| item.weight*used}.inject(:+),  # total weight
+   cost_matrix.last.last]                                               # total value
+end
+
+def get_used_items(items, cost_matrix)
+  i = cost_matrix.size - 1
+  currentCost = cost_matrix[0].size - 1
+  marked = cost_matrix.map{0}
+
+  while(i >= 0 && currentCost >= 0)
+    if(i == 0 && cost_matrix[i][currentCost] > 0 ) || (cost_matrix[i][currentCost] != cost_matrix[i-1][currentCost])
+      marked[i] = 1
+      currentCost -= items[i].weight
+    end
+    i -= 1
+  end
+  marked
+end
+
+def get_list_of_used_items_names(items, used_items)
+  items.zip(used_items).map{|item,used| item.name if used>0}.compact.join(', ')
+end
+
+if $0 == __FILE__
+  items = [
+    KnapsackItem['map'                   ,   9, 150], KnapsackItem['compass'            , 13,  35],
+    KnapsackItem['water'                 , 153, 200], KnapsackItem['sandwich'           , 50, 160],
+    KnapsackItem['glucose'               ,  15,  60], KnapsackItem['tin'                , 68,  45],
+    KnapsackItem['banana'                ,  27,  60], KnapsackItem['apple'              , 39,  40],
+    KnapsackItem['cheese'                ,  23,  30], KnapsackItem['beer'               , 52,  10],
+    KnapsackItem['suntan cream'          ,  11,  70], KnapsackItem['camera'             , 32,  30],
+    KnapsackItem['t-shirt'               ,  24,  15], KnapsackItem['trousers'           , 48,  10],
+    KnapsackItem['umbrella'              ,  73,  40], KnapsackItem['waterproof trousers', 42,  70],
+    KnapsackItem['waterproof overclothes',  43,  75], KnapsackItem['note-case'          , 22,  80],
+    KnapsackItem['sunglasses'            ,   7,  20], KnapsackItem['towel'              , 18,  12],
+    KnapsackItem['socks'                 ,   4,  50], KnapsackItem['book'               , 30,  10]
+  ]
+
+  names, weight, value = dynamic_programming_knapsack(items, 400)
+  puts
+  puts 'Dynamic Programming:'
+  puts
+  puts "Found solution: #{names}"
+  puts "total weight: #{weight}"
+  puts "total value: #{value}"
+end