inorder / preorder / postorder : Your tree « Collections « Ruby

1. Ruby
2. Collections
3. Your tree

inorder / preorder / postorder

class Tree


  attr_accessor :left
  attr_accessor :right
  attr_accessor :data

  def initialize(x=nil)
    @left = nil
    @right = nil
    @data = x
  end

  def insert(x)
    list = []
    if @data == nil
      @data = x
    elsif @left == nil
      @left = Tree.new(x)
    elsif @right == nil
      @right = Tree.new(x)
    else
      list << @left
      list << @right
      loop do
        node = list.shift
        if node.left == nil
          node.insert(x)
          break
        else
          list << node.left
        end
        if node.right == nil
          node.insert(x)
          break
        else
          list << node.right
        end
      end
    end
  end

  def traverse()
    list = []
    yield @data
    list << @left if @left != nil
    list << @right if @right != nil
    loop do
      break if list.empty?
      node = list.shift
      yield node.data
      list << node.left if node.left != nil
      list << node.right if node.right != nil
    end
  end

  def insert(x)
    if @data == nil
      @data = x
    elsif x <= @data
      if @left == nil
        @left = Tree.new x
      else
        @left.insert x
      end
    else
      if @right == nil
        @right = Tree.new x
      else
        @right.insert x
      end
    end
  end

  def inorder()
    @left.inorder {|y| yield y} if @left != nil
    yield @data
    @right.inorder {|y| yield y} if @right != nil
  end

  def preorder()
    yield @data
    @left.preorder {|y| yield y} if @left != nil
    @right.preorder {|y| yield y} if @right != nil
  end

  def postorder()
    @left.postorder {|y| yield y} if @left != nil
    @right.postorder {|y| yield y} if @right != nil
    yield @data
  end

end

items = [50, 20, 80, 10, 30, 70, 90, 5, 14,
         28, 41, 66, 75, 88, 96]

tree = Tree.new

items.each {|x| tree.insert(x)}

tree.inorder {|x| print x, " "}
print "\n"
tree.preorder {|x| print x, " "}
print "\n"
tree.postorder {|x| print x, " "}
print "\n"

 

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