python3 二叉树遍历

# 二叉树遍历  （此文用来纪念今天在 你好星球 面试被技术总监吊打，哈哈，还是要注重基础啊，不能忘）# 前序遍历：根节点->左子树->右子树# 中序遍历：左子树->根节点->右子树# 后续遍历：左子树->右子树->根节点# 二叉树构建如图#               a#              / \#             b   c#            / \   \#           d   e   f#          /    /  / \#         g    h  i   j#  节点数据结构class Node:    def __init__(self):        self.father= None        self.left= None        self.right= None        self.value= 0#  手撸二叉树 只为遍历 勿喷def generate_binary_tree(header):    b = Node()    c = Node()    d = Node()    e = Node()    f = Node()    g = Node()    h = Node()    i = Node()    j = Node()    b.value = 'b'    c.value = 'c'    d.value = 'd'    e.value = 'e'    f.value = 'f'    g.value = 'g'    h.value = 'h'    i.value = 'i'    j.value = 'j'    header.left = b    header.right = c    b.father = header    b.left = d    b.right = e    c.father = header    c.right = f    d.father = b    d.left = g    e.father = b    e.left = h    f.father = c    f.left = i    f.right = j    g.father = d    h.father = e    i.father = f    j.father = f# 前序遍历def preorder_traversal(header):    print(header.value,',',end='')    if header.left is not None:        preorder_traversal(header.left)    if header.right is not None:        preorder_traversal(header.right)# 中序遍历def inorder_traversal(header):    if header.left is not None:        inorder_traversal(header.left)    print(header.value,',',end='')    if header.right is not None:        inorder_traversal(header.right)# 后续遍历def postorder_traversal(header):    if header.left is not None:        postorder_traversal(header.left)    if header.right is not None:        postorder_traversal(header.right)    print(header.value,',',end='')# 执行header = Node()header.value = 'a'generate_binary_tree(header)print('前序遍历')preorder_traversal(header)print('中序遍历')inorder_traversal(header)print('后序遍历')postorder_traversal(header)

运行结果

前序遍历a ,b ,d ,g ,e ,h ,c ,f ,i ,j ,

中序遍历g ,d ,b ,h ,e ,a ,c ,i ,f ,j ,

后序遍历g ,d ,h ,e ,b ,i ,j ,f ,c ,a ,