python AVL树插入
我已经编写了一个python代码来实现。在编写代码时,我完全引用了我的伪代码。为了测试我创建的类,我编写了一个小测试代码app.py。它从用户获取节点数,并随机生成一个AVL树,如下所示:-python AVL树插入,python,avl-tree,Python,Avl Tree,我已经编写了一个python代码来实现。在编写代码时,我完全引用了我的伪代码。为了测试我创建的类,我编写了一个小测试代码app.py。它从用户获取节点数,并随机生成一个AVL树,如下所示:- from avl import * import random n = input("Enter number of nodes: ") l = random.sample(range(-10000,10001),n) root = node(l[0]) for x in l: root = ro
from avl import *
import random
n = input("Enter number of nodes: ")
l = random.sample(range(-10000,10001),n)
root = node(l[0])
for x in l:
root = root.insert(x)
print root.key
print "Your tree is\n"
root.inorder()
k = input("Enter integer to insert: ")
root.insert(k)
root.inorder()
k = input("Enter integer to delete: ")
root.delete(k)
root.inorder()
以下是AVL.py中保存的AVL树实现
class node:
def __init__(self,data):
self.left = None
self.right = None
self.key = data
self.height = 1
def calheight(self):
if not self.left:
if not self.right:
return 1
else:
return 1 + self.right.height
else:
if not self.right:
return 1 + self.left.height
else:
return max(self.left.height,self.right.height)+1
def rrotate(self):
p=self.left
self.left=p.right
p.right=self
self=p
self.right.calheight()
self.calheight()
return self
def lrotate(self):
p=self.right
self.right=p.left
p.left=self
self=p
self.left.calheight()
self.calheight()
return self
def dlrotate(self):
self.right = self.right.rrotate()
self = self.lrotate()
return self
def drrotate(self):
self.left = self.left.lrotate()
self = self.rrotate()
return self
def bal(self):
if not self.left:
if not self.right:
return 0
else:
return -(self.right.height)
else:
if not self.right:
return self.left.height
else:
return (self.left.height-self.right.height)
def insert(self,data):
if (data < self.key):
if not self.left:
self.left = node(data)
else:
self.left = self.left.insert(data)
if(self.bal() == 2):
print self.height,"\t",self.left.bal(),"\t",self.bal(),"\t",self.key
if(self.left.bal() == 1):
self = self.rrotate()
else:
self = self.drrotate()
elif (data > self.key):
if not self.right:
self.right = node(data)
else:
self.right = self.right.insert(data)
if(self.bal() == -2):
print self.height,"\t",self.right.bal(),"\t",self.bal(),"\t",self.key
if(self.right.bal() == -1):
self = self.lrotate()
else:
self = self.dlrotate()
else:
print "Key Already Exists"
self.height=self.calheight()
return self
def delete(self,data):
if (data < self.key):
self.left = self.left.delete(data)
elif (data > self.key):
self.right = self.right.delete(data)
else:
if not self.left:
if not self.right:
temp = self
self = None
else:
temp = self.right
self = temp
del temp
elif not self.right:
if not self.left:
temp = self
self = None
else:
temp = self.left
self = temp
del temp
else:
temp = self.right
while temp.left:
temp = temp.left
self.key = temp.key
self.right = self.right.delete(temp.key)
if self:
self.height=self.calheight()
if(self.bal() > 1):
if(self.left.bal() > 0):
self = self.rrotate()
else:
self = self.drrotate()
elif(self.bal() < -1):
if(self.right.bal() < 0):
self = self.lrotate()
else:
self = self.dlrotate()
return self
def inorder(self):
if self.left:
self.left.inorder()
print self.height,"\t",self.bal(),"\t",self.key
if self.right:
self.right.inorder()
app.py的输出在开始时似乎很好。但是,对于反复运行app.py(n值大于50),我开始注意到一些节点的绝对值平衡因子通常严格大于1甚至2。在一次运行中,它甚至给出了一个错误,因为它试图左旋转一个没有右子节点的节点
问题很可能在于插入函数。我反复检查了我的平衡条件和旋转算法。从理论上讲,它们似乎都很好。
如果有人能找到错误,我会很高兴。self在Python中是不可变的,当您从方法返回时,局部变量被释放,并且不会像c中的指针那样真正改变self。你必须想出另一种方法来处理旋转。例如,通过推断父节点来处理旋转
另请参见:我想处理该代码并尝试获取错误太难了。我想你可以运行你的代码,并得到一个列表,其中有10-20个节点插入了数字,从而产生了这样一个平衡因子。并修改代码,逐个插入数字,然后打印树。同时,用一张纸做同样的事情。并找出代码和树的不同之处。并尝试更正代码以使其相同。