问题描述
我正在用 Python 实现 BST。我已经编写了在 BST 中插入数据和搜索数据的函数。 问题是,我已经尝试了很多次来找出我犯了什么错误,但我一直无法正确地做。 我请求一些帮助。请帮帮我。
class Node:
def __init__(self,data):
self.data = data
self.left_ptr = None
self.right_ptr = None
class BinarySearchTree:
def __init__(self):
self.ptr_to_root = None
def insert(self,data):
'''
This feature/function helps the users to insert data into a Binary
Search Tree.
'''
# To insert,the first thing we have to do is
# creating a node :-
node = Node(data)
# We create a temperory pointer as we
# won't move ptr_to_root.
temp_ptr = self.ptr_to_root
# CASE 1 > If ptr_to_root is None i.e. If BST
# is empty :
if temp_ptr == None:
temp_ptr = node
# CASE 2 > If BST is not empty already :
while temp_ptr != None:
# Below is the pointer which will remain behind
# temp_ptr by one step.
r = temp_ptr
# If we already have the data present in BST,we
# cannot re-enter it. Hence,we simply exit the
# function.
if data == temp_ptr.data:
return
# If the data is having lesser value then temp_ptr's data,# then we move the temp_ptr to its left,or else the right.
if data < temp_ptr.data:
temp_ptr = temp_ptr.left_ptr
else:
temp_ptr = temp_ptr.right_ptr
# r is the tail pointer,which follows the temp_ptr.
# Eventually,we will compare if the value that we wanrt to insert
# is less or more then r.data,and accordingly insert the data desired.
if data < r.data:
r.left_ptr = node
else:
r.right_ptr = node
def search(self,data):
# If the BST is empty,then we do not
# have the element present in the BST for sure:
temp_ptr = self.ptr_to_root
# If BST is empty,then :
if temp_ptr == None:
return None
# If BST is not empty,we may or may not be
# finding the element in the tree :
while temp_ptr != None:
if data == temp_ptr.data:
return temp_ptr
elif data < temp_ptr.data:
temp_ptr = temp_ptr.left_ptr
else:
temp_ptr = temp_ptr.right_ptr
# If the element is not present in BST :
return None
当我运行上面的代码来插入一个元素然后搜索它时;即使我搜索已插入的元素,它也会返回“无”。 请帮忙!
解决方法
您的问题实际上非常简单,使用调试器几分钟就可以告诉您。您永远不会创建根节点。当您尝试将某些内容插入空树时,您设置了节点,但不保存它,因此树始终为空。改变这个:
.PHONY
一切正常。