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Diffstat (limited to 'lib/knapsack_solver/instance.rb')
| -rw-r--r-- | lib/knapsack_solver/instance.rb | 48 |
1 files changed, 48 insertions, 0 deletions
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 |