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@@ -1,322 +1,4 @@
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-class IntervalSkipList
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-  def initialize
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-    @head = HeadNode.new(max_height)
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-    @ranges = {}
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-  end
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-
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-  def max_height
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-    3
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-  end
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-
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-  def empty?
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-    head.forward[0].nil?
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-  end
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-
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-  def containing(n)
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-    containing = []
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-    cur_node = head
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-    (max_height - 1).downto(0) do |cur_level|
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-      while (next_node = cur_node.forward[cur_level]) && next_node.key <= n
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-        cur_node = next_node
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-        if cur_node.key == n
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-          return containing + (cur_node.markers - cur_node.endpoint_of)
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-        end
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-      end
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-      containing.concat(cur_node.forward_markers[cur_level])
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-    end
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-    containing
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-  end
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-
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-  def insert(range, marker)
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-    ranges[marker] = range
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-    first_node = insert_node(range.first)
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-    first_node.endpoint_of.push(marker)
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-    last_node = insert_node(range.last)
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-    last_node.endpoint_of.push(marker)
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-
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-    cur_node = first_node
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-    cur_level = first_node.height - 1
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-    while next_node_at_level_inside_range?(cur_node, cur_level, range)
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-      while can_ascend_from?(cur_node, cur_level) && next_node_at_level_inside_range?(cur_node, cur_level + 1, range)
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-        cur_level += 1
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-      end
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-      cur_node = mark_forward_path_at_level(cur_node, cur_level, marker)
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-    end
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-
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-    while node_inside_range?(cur_node, range)
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-      while can_descend_from?(cur_level) && next_node_at_level_outside_range?(cur_node, cur_level, range)
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-        cur_level -= 1 
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-      end
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-      cur_node = mark_forward_path_at_level(cur_node, cur_level, marker)
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-    end
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-  end
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-
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-  def delete(marker)
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-    range = ranges[marker]
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-    path_to_first_node = make_path
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-    first_node = find(range.first, path_to_first_node)
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-
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-    cur_node = first_node
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-    cur_level = first_node.height - 1
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-    while next_node_at_level_inside_range?(cur_node, cur_level, range)
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-      while can_ascend_from?(cur_node, cur_level) && next_node_at_level_inside_range?(cur_node, cur_level + 1, range)
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-        cur_level += 1
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-      end
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-      cur_node = unmark_forward_path_at_level(cur_node, cur_level, marker)
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-    end
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-
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-    while node_inside_range?(cur_node, range)
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-      while can_descend_from?(cur_level) && next_node_at_level_outside_range?(cur_node, cur_level, range)
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-        cur_level -= 1
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-      end
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-      cur_node = unmark_forward_path_at_level(cur_node, cur_level, marker)
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-    end
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-    last_node = cur_node
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-
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-    first_node.endpoint_of.delete(marker)
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-    if first_node.endpoint_of.empty?
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-      first_node.delete(path_to_first_node)
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-    end
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-
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-    last_node.endpoint_of.delete(marker)
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-    if last_node.endpoint_of.empty?
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-      path_to_last_node = make_path
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-      find(range.last, path_to_last_node)
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-      last_node.delete(path_to_last_node)
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-    end
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-  end
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-
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-  protected
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-  attr_reader :head, :ranges
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-  
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-  def insert_node(key)
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-    path = make_path
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-    found_node = find(key, path)
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-    if found_node && found_node.key == key
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-      return found_node
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-    else
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-      return Node.new(key, next_node_height, path)
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-    end
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-  end
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-
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-  def delete_node(key)
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-    path = make_path
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-    found_node = find(key, path)
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-    found_node.delete(path) if found_node.key == key
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-  end
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-  
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-  def find(key, path)
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-    cur_node = head
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-    (max_height - 1).downto(0) do |cur_level|
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-      while (next_node = cur_node.forward[cur_level]) && next_node.key < key
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-        cur_node = next_node
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-      end
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-      path[cur_level] = cur_node
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-    end
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-    cur_node.forward[0]
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-  end
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-
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-  def make_path
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-    Array.new(max_height, nil)
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-  end
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-
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-  def next_node_height
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-    nil
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-  end
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-
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-  def can_ascend_from?(node, level)
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-    level < node.height - 1
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-  end
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-
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-  def can_descend_from?(level)
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-    level > 0
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-  end
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-
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-  def node_inside_range?(node, range)
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-    node.key < range.last
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-  end
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-
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-  def next_node_at_level_inside_range?(node, level, range)
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-    node.forward[level] && node.forward[level].key <= range.last
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-  end
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-
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-  def next_node_at_level_outside_range?(node, level, range)
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-    (node.forward[level].nil? || node.forward[level].key > range.last)
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-  end
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-
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-  def mark_forward_path_at_level(node, level, marker)
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-    node.forward_markers[level].push(marker)
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-    next_node = node.forward[level]
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-    next_node.markers.push(marker)
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-    node = next_node
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-  end
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-
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-  def unmark_forward_path_at_level(node, level, marker)
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-    node.forward_markers[level].delete(marker)
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-    next_node = node.forward[level]
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-    next_node.markers.delete(marker)
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-    node = next_node
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-  end
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-
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-  def nodes
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-    nodes = []
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-    cur_node = head.forward[0]
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-    until cur_node.nil?
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-      nodes << cur_node
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-      cur_node = cur_node.forward[0]
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-    end
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-    nodes
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-  end
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-
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-  class HeadNode
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-    attr_reader :height, :forward, :forward_markers
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-
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-    def initialize(height)
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-      @height = height
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-      @forward = Array.new(height, nil)
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-      @forward_markers = Array.new(height) {|i| []}
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-    end
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-  end
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-
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-  class Node < HeadNode
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-    attr_reader :key, :markers, :endpoint_of
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-
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-    def initialize(key, height, path)
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-      super(height)
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-      @key = key
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-      @markers = []
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-      @endpoint_of = []
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-      update_forward_pointers(path)
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-      promote_markers(path)
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-    end
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-
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-    def delete(path)
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-      0.upto(height - 1) do |i|
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-        path[i].forward[i] = forward[i]
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-      end
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-      demote_markers(path)
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-    end
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-
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-    protected
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-
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-    def update_forward_pointers(path)
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-      0.upto(height - 1) do |i|
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-        forward[i] = path[i].forward[i]
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-        path[i].forward[i] = self
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-      end
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-    end
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-
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-    def promote_markers(path)
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-      promoted = []
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-      new_promoted = []
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-      0.upto(height - 1) do |i|
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-        incoming_markers = path[i].forward_markers[i]
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-        markers.concat(incoming_markers)
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-
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-        incoming_markers.each do |marker|
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-          if can_be_promoted_higher?(marker, i)
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-            new_promoted.push(marker)
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-            forward[i].delete_marker_from_path(marker, i, forward[i+1])
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-          else
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-            forward_markers[i].push(marker)
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-          end
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-        end
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-
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-        promoted.each do |marker|
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-          if can_be_promoted_higher?(marker, i)
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-            new_promoted.push(marker)
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-            forward[i].delete_marker_from_path(marker, i, forward[i+1])            
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-          else
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-            forward_markers[i].push(marker)
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-          end
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-        end
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-
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-        promoted = new_promoted
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-        new_promoted = []
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-      end
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-    end
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-
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-    def demote_markers(path)
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-      demoted = []
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-      new_demoted = []
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-
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-      (height - 1).downto(0) do |i|
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-        incoming_markers = path[i].forward_markers[i].dup
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-        incoming_markers.each do |marker|
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-          unless node_in_range_reachable_from_level?(marker, i)
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-            path[i].forward_markers[i].delete(marker)
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-            new_demoted.push(marker)
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-          end
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-        end
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-
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-        demoted.each do |marker|
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-          path[i+1].place_marker_on_inbound_path(marker, i, path[i])
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-
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-          if forward[i].markers.include?(marker)
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-            path[i].forward_markers[i].push(marker)
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-          else
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-            new_demoted.push(marker)
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-          end
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-        end
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-        
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-        demoted = new_demoted
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-        new_demoted = []
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-      end
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-
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-      demoted = []
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-      new_demoted = []
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-
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-      (height - 1).downto(0) do |i|
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-        forward_markers[i].each do |marker|
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-          new_demoted.push(marker) unless path[i].forward_markers[i].include?(marker)
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-        end
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-
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-        demoted.each do |marker|
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-          forward[i].place_marker_on_outbound_path(marker, i, forward[i + 1])
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-          new_demoted.push(marker) unless path[i].forward_markers[i].include?(marker)
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-        end
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-
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-        demoted = new_demoted
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-        new_demoted = []
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-      end
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-    end
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-
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-    def node_in_range_reachable_from_level?(marker, level)
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-      level.upto(height - 1) do |i|
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-        return true if forward[i].markers.include?(marker)
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-      end
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-      false
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-    end
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-
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-    def can_be_promoted_higher?(marker, level)
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-      level < height - 1 && forward[level + 1] && forward[level + 1].markers.include?(marker)
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-    end
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-
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-    def delete_marker_from_path(marker, level, terminus)
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-      cur_node = self
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-      until cur_node == terminus
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-        cur_node.forward_markers[level].delete(marker)
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-        cur_node.markers.delete(marker)
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-        cur_node = cur_node.forward[level]
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-      end
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-    end
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-
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-    def place_marker_on_outbound_path(marker, level, terminus)
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-      cur_node = self
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-      until cur_node == terminus
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-        cur_node.forward_markers[level].push(marker)
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-        cur_node.markers.push(marker)
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-        cur_node = cur_node.forward[level]
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-      end
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-    end
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-
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-    def place_marker_on_inbound_path(marker, level, terminus)
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-      cur_node = self
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-      until cur_node == terminus
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-        cur_node.forward_markers[level].push(marker)
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-        cur_node = cur_node.forward[level]
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-        cur_node.markers.push(marker)
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-      end
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-    end
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-  end
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-end
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\ No newline at end of file
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+dir = File.dirname(__FILE__)
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+require "#{dir}/interval_skip_list/interval_skip_list.rb"
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+require "#{dir}/interval_skip_list/head_node.rb"
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+require "#{dir}/interval_skip_list/node.rb"
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\ No newline at end of file