70 lines
1.2 KiB
Ruby
70 lines
1.2 KiB
Ruby
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require_relative 'node.rb'
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class LinkedList
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include Enumerable
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attr_accessor :length
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def initialize
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@length = 0
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@index = -1
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end
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def [](pos)
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return if pos >= length || pos < 0 # bounds check
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delta = pos > @index ? 1 : -1 # set direction
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until @index == pos # traverse
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@current = delta == 1 ? @current.next : @current.previous
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@index += delta
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end
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@current.data
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end
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def []=(pos, data)
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return if pos < 0 # bounds check
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create_head if index == -1
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delta = pos > @index ? 1 : -1 # set direction
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until @index == pos # traverse
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create_next_node if @index == @length - 1 # create missing nodes
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@current = delta == 1 ? @current.next : @current.previous
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@index += delta
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end
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@current.data = data
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end
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def <<(value)
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self[@length] = value
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end
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def each
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(0...@length).each do |x|
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yield self[x]
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end
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end
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def first
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@head.data
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end
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def last
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@tail.data
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end
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private
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def create_head
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@head = Node.new
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@tail = @head
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@index = 0
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@length = 1
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end
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def create_next_node
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@tail.next = Node.new
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@tail = @tail.next
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@length += 1
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end
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end
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