Class: Knapsacker::Node

Inherits:
Object
  • Object
show all
Defined in:
lib/knapsacker/node.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(item_index, item, upper_bound, parent) ⇒ Node

Returns a new instance of Node.



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# File 'lib/knapsacker/node.rb', line 8

def initialize(item_index, item, upper_bound, parent)
  @item_index  = item_index
  @item        = item
  @upper_bound = upper_bound
  @parent      = parent
end

Instance Attribute Details

#item_index ⇒ Object (readonly)

Returns the value of attribute item_index.



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# File 'lib/knapsacker/node.rb', line 5

def item_index
  @item_index
end

#negative_child ⇒ Object

Returns the value of attribute negative_child.



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# File 'lib/knapsacker/node.rb', line 3

def negative_child
  @negative_child
end

#positive_child ⇒ Object

Returns the value of attribute positive_child.



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# File 'lib/knapsacker/node.rb', line 4

def positive_child
  @positive_child
end

#upper_bound ⇒ Object (readonly)

Returns the value of attribute upper_bound.



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# File 'lib/knapsacker/node.rb', line 6

def upper_bound
  @upper_bound
end

Instance Method Details

#<=>(other) ⇒ Object 



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# File 'lib/knapsacker/node.rb', line 15

def <=>(other)
  if other.upper_bound == upper_bound
    other.item_index <=> item_index
  else
    other.upper_bound <=> upper_bound
  end
end

#cap_negative_child! ⇒ Object 



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# File 'lib/knapsacker/node.rb', line 23

def cap_negative_child!
  @negative_child = :cap
end

#cap_positive_child! ⇒ Object 



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# File 'lib/knapsacker/node.rb', line 27

def cap_positive_child!
  @positive_child = :cap
end

#cost ⇒ Object 



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# File 'lib/knapsacker/node.rb', line 31

def cost
  if @parent
    @parent.cost + (@item ? @item.cost : 0)
  else
    0
  end
end

#items ⇒ Object 



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# File 'lib/knapsacker/node.rb', line 39

def items
  if @parent
    if @item
      @parent.items << @item
    else
      @parent.items
    end
  else
    []
  end
end

#leaf? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/knapsacker/node.rb', line 51

def leaf?
  @negative_child == :cap && @positive_child == :cap
end

#negative_child_growable? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/knapsacker/node.rb', line 55

def negative_child_growable?
  @negative_child.nil?
end

#positive_child_growable? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/knapsacker/node.rb', line 59

def positive_child_growable?
  @positive_child.nil?
end

#value ⇒ Object 



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# File 'lib/knapsacker/node.rb', line 63

def value
  if @parent
    @parent.value + (@item ? @item.value : 0)
  else
    0
  end
end