From 7b34bab6af30df9cfca7df9e0c644a0ea967ff04 Mon Sep 17 00:00:00 2001
From: sucanjan <sucanjan@fit.cvut.cz>
Date: Wed, 14 Feb 2018 21:57:30 +0100
Subject: Initial commit

---
 lib/knapsack_solver/instance.rb | 48 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 lib/knapsack_solver/instance.rb

(limited to 'lib/knapsack_solver/instance.rb')

diff --git a/lib/knapsack_solver/instance.rb b/lib/knapsack_solver/instance.rb
new file mode 100644
index 0000000..1fe3ecc
--- /dev/null
+++ b/lib/knapsack_solver/instance.rb
@@ -0,0 +1,48 @@
+module KnapsackSolver
+  # This class represents an instance of a 0/1 knapsack problem.
+  class Instance
+    # Initializes instance of a 0/1 knapsack problem.
+    #
+    # @param capacity [Integer] weight capacity of the knapsack
+    # @param things [Array<Thing>] things which can be put into the knapsack
+    def initialize(capacity, things)
+      @weight_capacity = capacity
+      @things = things
+    end
+
+    # Creates new instance of a 0/1 knapsack problem.
+    #
+    # @param line [String] line that describes an instance of a 0/1 knapsack problem
+    # @return [Instance] instance of the 0/1 knapsack problem
+    def self.parse(line)
+      thing = Struct.new(:price, :weight, :index)
+      # Rozdelit riadok na slova a previest na cisla
+      items = split_line(line)
+      # Inicializacia premennych
+      things = items.drop(1).each_slice(2).with_index.each_with_object([]) do |(s, i), o|
+        o << thing.new(s[0], s[1], i)
+      end
+      Instance.new(items[0], things)
+    end
+
+    # Splits line that describes an instance of a 0/1 knapsack problem to
+    # individual numbers.
+    #
+    # @param line [String] line that describes an instance of a 0/1 knapsack problem
+    # @return [Array<Integer>] integer numbers from the line
+    def self.split_line(line)
+      items = line.split.map! do |i|
+        n = Integer(i)
+        raise StandardError, 'dataset: instance desctiption contains negative number' if n < 0
+        n
+      end
+      raise StandardError, 'dataset: missing knapsack capacity' if items.empty?
+      raise StandardError, 'dataset: missing pairs (price, weight)' if items.size.even?
+      items
+    rescue ArgumentError
+      raise StandardError, 'dataset: instance desctiption does not contain only integers'
+    end
+
+    attr_reader :weight_capacity, :things
+  end
+end
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