Coding for Interviews: Tree Traversal (1)

1. Explain what the big three depth-first tree traversals are and what to consider when implementing them.

The big three depth-first tree traversals are ways to traverse a tree. "Depth-first" means that they will traverse to the lowest depth before moving on to the next node. The three ways are inorder (left, root, right), preorder (root, left, right) and postorder (left, right, root). 

Coding for Interviews: Tree Traversal (2)

# 2 .Implement a simple binary (non-search) tree node data structure in your favorite programming language and write the following methods: 
# (1) print nodes pre-order, (2) print nodes in-order, (3) print nodes post-order.

class Node:
	def __init__(self, left=None, right=None, data=None):
		self.left = left
		self.right = right
		self.data = data

class Tree:
	def __init__(self, root):
		self.root = root

	def preorder(self, node):
		if(node):
			print node.data
			self.preorder(node.left)
			self.preorder(node.right)

	def inorder(self, node):
		if(node):
			self.inorder(node.left)
			print node.data
			self.inorder(node.right)

	def postorder(self, node):
		if(node):
			self.postorder(node.left)
			self.postorder(node.right)
			print node.data

root = Node(
			Node(None, Node(Node(None, None, 29), Node(None, None, 1), 3), 4), 
			Node(Node(None, None, 45), Node(None, None, 13), 14), 
		"farts")
tree = Tree(root)
# tree.preorder(root)
# tree.inorder(root)
tree.postorder(root)