Created
October 17, 2014 17:07
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Tree traversal in python
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from collections import namedtuple | |
from sys import stdout | |
Node = namedtuple('Node', 'data, left, right') | |
tree = Node(1, | |
Node(2, | |
Node(4, | |
Node(7, None, None), | |
None), | |
Node(5, None, None)), | |
Node(3, | |
Node(6, | |
Node(8, None, None), | |
Node(9, None, None)), | |
None)) | |
def printwithspace(i): | |
stdout.write("%i " % i) | |
def preorder(node, visitor = printwithspace): | |
if node is not None: | |
visitor(node.data) | |
preorder(node.left, visitor) | |
preorder(node.right, visitor) | |
def inorder(node, visitor = printwithspace): | |
if node is not None: | |
inorder(node.left, visitor) | |
visitor(node.data) | |
inorder(node.right, visitor) | |
def postorder(node, visitor = printwithspace): | |
if node is not None: | |
postorder(node.left, visitor) | |
postorder(node.right, visitor) | |
visitor(node.data) | |
def levelorder(node, more=None, visitor = printwithspace): | |
if node is not None: | |
if more is None: | |
more = [] | |
more += [node.left, node.right] | |
visitor(node.data) | |
if more: | |
levelorder(more[0], more[1:], visitor) | |
stdout.write(' preorder: ') | |
preorder(tree) | |
stdout.write('\n inorder: ') | |
inorder(tree) | |
stdout.write('\n postorder: ') | |
postorder(tree) | |
stdout.write('\nlevelorder: ') | |
levelorder(tree) | |
stdout.write('\n') |
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