Inorder traversal of binary tree using stack in ruby

Ruby program for Inorder traversal of binary tree using stack. Here problem description and explanation.

#  Ruby program for
#  Inorder traversal without recursion
#  Using stack

#  Binary Tree node
class TreeNode 
	# Define the accessor and reader of class TreeNode
	attr_reader :data, :left, :right
	attr_accessor :data, :left, :right
	#  Make a tree node
	def initialize(data) 
		#  Set node data
		self.data = data
		self.left = nil
		self.right = nil
	end
end

class StackNode 
	# Define the accessor and reader of class StackNode
	attr_reader :element, :next
	attr_accessor :element, :next
	def initialize(element) 
		self.element = element
		self.next = nil
	end
end

#  Stack Class
class MyStack 
	# Define the accessor and reader of class MyStack
	attr_reader :top, :size
	attr_accessor :top, :size
	def initialize() 
		self.top = nil
		self.size = 0
	end

	#  Add new element into stack
	def push(element) 
		#  Create new node
		node = StackNode.new(element)
		node.next = self.top
		#  new node is new top
		self.top = node
		#  Increase the size
		self.size += 1
	end

	#  Remove top element of the stack
	def pop() 
		if (self.top != nil) 
			#  next node is new top
			self.top = self.top.next
			#  Reduce size
			self.size -= 1
		end

	end

	#  Returns the status of empty or non empty stacks
	def isEmpty() 
		if (self.size > 0 && self.top != nil) 
			return false
		else
			return true
		end
	end

	#  Return top element of stack
	def peek() 
		if (self.isEmpty()) 
			return nil
		end
		return self.top.element
	end

end

class BinaryTree 
	# Define the accessor and reader of class BinaryTree
	attr_reader :root
	attr_accessor :root
	def initialize() 
		self.root = nil
	end
	#  Display Inorder view of binary tree
	def inorder() 
		if (self.root != nil) 
			#  Make new stack
			s = MyStack.new()
			node = self.root
			#  Display tree element
			while (!s.isEmpty() || node != nil) 
				if (node != nil) 
					#  Add current node
					s.push(node)
					#  Visit to left subtree
					node = node.left
				else
 
					#  When node is null
					#  Get stack top element
					node = s.peek()
					#  Display node value
					print(" ", node.data)
					#  Remove top element of the stack
					s.pop()
					#  Visit to left subtree of current node
					node = node.right
				end

			end

		else
 
			print("Empty Linked List\n")
		end

	end

end

def main() 
	#  Create new tree
	tree = BinaryTree.new()
	#    Construct Binary Tree
	#    -----------------------
	#        15
	#       /  \
	#      24   54
	#     /    /  \
	#    35   62   13
	#  Add tree nodes
	tree.root = TreeNode.new(15)
	tree.root.left = TreeNode.new(24)
	tree.root.right = TreeNode.new(54)
	tree.root.right.right = TreeNode.new(13)
	tree.root.right.left = TreeNode.new(62)
	tree.root.left.left = TreeNode.new(35)
	#  Display result
	tree.inorder()
end

main()

Output

 35 24 15 62 54 13


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