Nov 7, 2020 · Oct 21, 2020 · Nov 5, 2020 · Nov 5, 2020
diff --git a/data-structures/zigzagtraversal_iterative.py b/data-structures/zigzagtraversal_iterative.py
 classNode:
 """
    A Node has data variable and pointers to its left and right nodes.
    """

 def__init__(self,data):
 self.left=None
 self.right=None
 self.data=data

 defmake_tree()->Node:
 root=Node(1)
 root.left=Node(2)
 root.right=Node(3)
 root.left.left=Node(4)
 root.left.right=Node(5)
 returnroot

 defzigzag_iterative(root:Node):
 """
    ZigZag traverse by iterative method: Print node left to right and right to left, alternatively.
    """
 ifroot==None:
 return

 # two stacks to store alternate levels
 s1= []# For levels to be printed from right to left
 s2= []# For levels to be printed from left to right

 # append first level to first stack 's1'
 s1.append(root)

 # Keep printing while any of the stacks has some nodes
 whilenotlen(s1)==0ornotlen(s2)==0:

 # Print nodes of current level from s1 and append nodes of next level to s2
 whilenotlen(s1)==0:
 temp=s1[-1]
 s1.pop()
 print(temp.data,end=" ")

 # Note that is left is appended before right
 iftemp.left:
 s2.append(temp.left)
 iftemp.right:
 s2.append(temp.right)

 # Print nodes of current level from s2 and append nodes of next level to s1
 whilenotlen(s2)==0:
 temp=s2[-1]
 s2.pop()
 print(temp.data,end=" ")

 # Note that is rightt is appended before left
 iftemp.right:
 s1.append(temp.right)
 iftemp.left:
 s1.append(temp.left)

 defmain():# Main function for testing.
 """
    Create binary tree.
    """
 root=make_tree()
 print("\nZigzag order traversal(iterative) is: ")
 zigzag_iterative(root)
 print()


 if__name__=="__main__":
 importdoctest

 doctest.testmod()
 main()
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,75 @@
		classNode:
		"""
		A Node has data variable and pointers to its left and right nodes.
		"""

		def__init__(self,data):
		self.left=None
		self.right=None
		self.data=data

		defmake_tree()->Node:
		root=Node(1)
		root.left=Node(2)
		root.right=Node(3)
		root.left.left=Node(4)
		root.left.right=Node(5)
		returnroot

		defzigzag_iterative(root:Node):
		"""
		ZigZag traverse by iterative method: Print node left to right and right to left, alternatively.
		"""
		ifroot==None:
		return

		# two stacks to store alternate levels
		s1= []# For levels to be printed from right to left
		s2= []# For levels to be printed from left to right

		# append first level to first stack 's1'
		s1.append(root)

		# Keep printing while any of the stacks has some nodes
		whilenotlen(s1)==0ornotlen(s2)==0:

		# Print nodes of current level from s1 and append nodes of next level to s2
		whilenotlen(s1)==0:
		temp=s1[-1]
		s1.pop()
		print(temp.data,end=" ")

		# Note that is left is appended before right
		iftemp.left:
		s2.append(temp.left)
		iftemp.right:
		s2.append(temp.right)

		# Print nodes of current level from s2 and append nodes of next level to s1
		whilenotlen(s2)==0:
		temp=s2[-1]
		s2.pop()
		print(temp.data,end=" ")

		# Note that is rightt is appended before left
Copy link Contributor hemanth-kotagiriNov 5, 2020 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. Just one small change.`rightt` to`right`. Writing well-documented code is extremely important. Try fixing any other issues of the same kind. Code LGTM. Copy link ContributorAuthor SakshiiAgrawalNov 5, 2020 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. sure, will do it
		iftemp.right:
		s1.append(temp.right)
		iftemp.left:
		s1.append(temp.left)

		defmain():# Main function for testing.
		"""
		Create binary tree.
		"""
		root=make_tree()
		print("\nZigzag order traversal(iterative) is: ")
		zigzag_iterative(root)
		print()


		if__name__=="__main__":
		importdoctest

		doctest.testmod()
		main()