Python二叉树定义与遍历方法实例分析

#coding:utf-8
'BiTree'
class Node(object):
  'Node Defination'
  def __init__(self,item):
    self.item = item
    self.left = None
    self.right = None
class Tree(object):
  'Bitree Defination'
  def __init__(self):
    self.root = None
  def add(self,item):
    node = Node(item)
    if self.root is None:
      self.root = node
    else:
      q = [self.root]
      while True:
        pop_node = q.pop(0)
        if pop_node.left is None:
          pop_node.left = node
          return
        elif pop_node.right is None:
          pop_node.right = node
          return
        else:
          q.append(pop_node.left)
          q.append(pop_node.right)
  def traverse(self):#层次遍历
    if self.root is None:
      return None
    q = [self.root]
    res = [self.root.item]
    while q != []:
      pop_node = q.pop(0)
      if pop_node.left is not None:
        q.append(pop_node.left)
        res.append(pop_node.left.item)
      if pop_node.right is not None:
        q.append(pop_node.right)
        res.append(pop_node.right.item)
    return res
  def preorder(self,root): #先序遍历
    if root is None:
      return []
    result = [root.item]
    left_item = self.preorder(root.left)
    right_item = self.preorder(root.right)
    return result + left_item + right_item
  def inorder(self,root): #中序遍历
    if root is None:
      return []
    result = [root.item]
    left_item = self.inorder(root.left)
    right_item = self.inorder(root.right)
    return left_item + result + right_item
  def postorder(self,root): #后序遍历
    if root is None:
      return []
    result = [root.item]
    left_item = self.postorder(root.left)
    right_item = self.postorder(root.right)
    return left_item + right_item + result
if __name__=='__main__':
  t = Tree()
  for i in range(10):
    t.add(i)
  print "层序遍历:",t.traverse()
  print "先序遍历:",t.preorder(t.root)
  print "中序遍历:",t.inorder(t.root)
  print "后序遍历:",t.postorder(t.root)

if __name__=='__main__':
“Make a script both importable and executable”

#test.py
def func():
 print "we are in %s"%__name__
if __name__ == '__main__':
 func()

#testtest
from test import func
func()