DFS Recursive Binary Tree Traversal

dfs_recursive_binary_tree_traversal.py

# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right


def recursive_inorder_traversal(root: TreeNode):
  if not root:
    return
  
  left = recursive_inorder_traversal(root.left)
  # This where we process the node.
  # Notice we do left -> root -> right
  print(root.val)
  right = recursive_inorder_traversal(root.right)
  return
  
 
def recursive_preorder_traversal(root: TreeNode):
  if not root:
    return
  
  # This where we process the node.
  # Notice we do root -> left -> right
  print(root.val)
  left = recursive_inorder_traversal(root.left)
  right = recursive_inorder_traversal(root.right)
  return
  
  
def recursive_postorder_traversal(root: TreeNode):
  if not root:
    return
  
  # This where we process the node.
  # Notice we do root left -> right -> root
  left = recursive_inorder_traversal(root.left)
  right = recursive_inorder_traversal(root.right)
  print(root.val)
  return