在树的中序遍历中查找第 N 个节点的 Python 程序
当需要使用二叉树的中序遍历找到第n个节点时，创建一个二叉树类，其中包含设置根元素、向左或向右添加元素、执行顺序遍历等方法。类的一个实例被创建，它可以用来访问方法。
以下是相同的演示-
示例
class BinaryTree_struct:
def __init__(self, key=None):
self.key= key
self.left= None
self.right= None
def set_root(self, key):
self.key= key
def inorder_nth(self, n):
return self.inorder_nth_helper_fun(n, [])
def inorder_nth_helper_fun(self, n, in_ord):
ifself.leftis not None:
temp = self.left.inorder_nth_helper_fun(n, in_ord)
if temp is not None:
return temp
in_ord.append(self)
if n == len(in_ord):
return self
ifself.rightis not None:
temp = self.right.inorder_nth_helper_fun(n, in_ord)
if temp is not None:
return temp
def insert_t0_left(self, new_node):
self.left= new_node
def insert_to_right(self, new_node):
self.right= new_node
def search_elem(self, key):
ifself.key== key:
return self
ifself.leftis not None:
temp = self.left.search_elem(key)
if temp is not None:
return temp
ifself.rightis not None:
temp = self.right.search_elem(key)
return temp
return None
btree_instance = None
print('Menu (this assumes no duplicate keys)')
print('insert at root')
print('insert left of ')
print('insert right of ')
print('inorder ')
print('quit')
while True:
do = input('What would you like to do? ').split()
operation = do[0].strip().lower()
if operation == 'insert':
data = int(do[1])
new_node = BinaryTree_struct(data)
suboperation = do[2].strip().lower()
if suboperation == 'at':
btree_instance = new_node
else:
position = do[4].strip().lower()
key = int(position)
ref_node = None
if btree_instance is not None:
ref_node = btree_instance.search_elem(key)
if ref_node is None:
print('No such key.')
continue
if suboperation == 'left':
ref_node.insert_t0_left(new_node)
elif suboperation == 'right':
ref_node.insert_to_right(new_node)
elif operation == 'inorder':
if btree_instance is not None:
index = int(do[1].strip().lower())
node = btree_instance.inorder_nth(index)
if node is not None:
print('nth term of inorder traversal: {}'.format(node.key))
else:
print('The index exceeds maximum possible index.')
else:
print('The tree is empty...')
elif operation == 'quit':
break输出结果Menu (this assumes no duplicate keys) insert at root insert left of insert right of inorder quit What would you like to do? insert 5 at root What would you like to do? insert 6 left of 5 What would you like to do? insert 8 right of 5 What would you like to do? inorder 5 The index exceeds maximum possible index. What would you like to do? 6 6
解释
创建了具有所需属性的“BinaryTree_struct”类。
它有一个“init”函数，用于将左右节点设置为“无”。
它有一个“set_root”方法，可以帮助设置二叉树的根。
另一种名为“inorder_nth”的方法使用递归执行中序遍历。
因此，它旁边定义了一个辅助函数。
定义了另一个名为“insert_to_right”的方法，它有助于将元素添加到根节点的右侧。
定义了一个名为“insert_to_left”的方法，它有助于将元素添加到根节点的左侧。
定义了一个名为“search_elem”的方法，它有助于搜索特定元素。
创建了“BinaryTree_struct”类的对象。
用户输入用于需要执行的操作。
根据用户的选择，执行操作。
相关输出显示在控制台上。