python 建立最简单二叉树

#!/usr/bin/env python
#-*- coding:utf-8 -*-


class Tree:

	def __init__(self, cargo, left = None, right = None):
		self.cargo = cargo
		self.left = left
		self.right = right
	
	def __str__(self):
		return str(self.cargo)

tree = Tree(1, Tree(2), Tree(3))
print (tree)

def total(atree):   # get sum of the tree
	if atree == None:
		return 0
	return total(atree.left) + total(atree.right) + atree.cargo

print (total(tree)) # 1 + 2 +3 = 6


def printTree(atree):
	if atree == None:
		return 
	print (atree.cargo)
	printTree(atree.left)
	printTree(atree.right)
print ("preorder:")
printTree(tree)

def printTreePostorder(atree):
	if atree == None:
		return 
	printTreePostorder(atree.left)
	printTreePostorder(atree.right)
	print (atree.cargo)

print ("Postorder")
printTreePostorder(tree)

def printTreeInorder(atree):
	if atree == None:
		return 
	printTreeInorder(atree.left)
	print (atree.cargo)
	printTreeInorder(atree.right)


print ("Inorder")
printTreeInorder(tree)
	
input()

转自 Linux Python