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(['1','2','3',"4","5","6"])
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)