二叉树的遍历python 代码

 __author__ = "WSX"

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

 class tree:
     def __init__(self, L):
         self.val = L

     def bulid(self,root, i):    #将列表转化建立二叉树
         if i < len(self.val):
             root = Node(val = self.val[i])
             root.left = self.bulid(root.left, 2*i+1)
             root.right = self.bulid(root.right, 2*i+2)
             return root
         return root

     def preTraverse(self, tree_):
         root = tree_
         if root:
             print(root.val)
             self.preTraverse(root.left)
             self.preTraverse(root.right)

     def midTraverse(self, tree_):
         root = tree_
         if root:
             self.preTraverse(root.left)
             print(root.val)
             self.preTraverse(root.right)

     def postTraverse(self, tree_):
         root = tree_
         if root:
             self.preTraverse(root.left)
             self.preTraverse(root.right)
             print(root.val)

     def cengci(self, tree_):
         root = tree_
         queue = [root]  #借助队列
         while root and len(queue)!= 0:
             print(queue[0].val)  #visit
             if queue[0].left:
                 queue.append(queue[0].left)
             if queue[0].right:
                 queue.append(queue[0].right)
             queue.pop(0)

 T = tree(['','','',"","",""])
 root = T.bulid(Node(), 0)
 print("preTraverse"); T.preTraverse(root)
 print("postTraverse");T.postTraverse(root)
 print("midTraverse");T.midTraverse(root)
 print("cengci");T.cengci(root)

非递归遍历：

 __author__ = "WSX"

 def pre(root):
     if not root:
         return None
     stack = [root]
     res = []
     while stack:
         res.append(root.val)
         if root.right:
             stack.append(root.right)
         if root.left:
             stack.append(root.left)
         root = stack.pop()
     return res

 def inOrderTraverse(node):
     stack = []
     pos = node
     while pos is not None or len(stack) > 0:
         if pos is not None:
             stack.append(pos)
             pos = pos.left
         else:
             pos = stack.pop()
             print(pos.val)
             pos = pos.right

 def postOrderTraverse(node):
     stack = [node]
     stack2 = []
     while len(stack) > 0:
         node = stack.pop()
         stack2.append(node)
         if node.left is not None:
             stack.append(node.left)
         if node.right is not None:
             stack.append(node.right)
     while len(stack2) > 0:
         print(stack2.pop().val)