# -*- coding: utf-8 -*-
'''
An auto-balanced binary tree!
'''
import math
import random
class my_queue:
def __init__(self):
self.data = []
self.head = 0
self.tail = 0
def isEmpty(self):
return self.head == self.tail
def push(self,data):
self.data.append(data)
self.tail = self.tail + 1
def pop(self):
ret = self.data[self.head]
self.head = self.head + 1
return ret
def count(self):
return self.tail - self.head
def print(self):
print(self.data)
print("**************")
print(self.data[self.head:self.tail])
class my_node:
def __init__(self,data):
self.data = data
self.left = None
self.right = None
self.height = 1
def getdata(self):
return self.data
def getleft(self):
return self.left
def getright(self):
return self.right
def getheight(self):
return self.height
def setdata(self,data):
self.data = data
return
def setleft(self,node):
self.left = node
return
def setright(self,node):
self.right = node
return
def setheight(self,height):
self.height = height
return
def getheight(node):
if node is None:
return 0
return node.getheight()
def my_max(a,b):
if a > b:
return a
return b
def leftrotation(node):
r'''
A B
/ \ / \
B C Bl A
/ \ --> / / \
Bl Br UB Br C
/
UB
UB = unbalanced node
'''
print("left rotation node:",node.getdata())
ret = node.getleft()
node.setleft(ret.getright())
ret.setright(node)
h1 = my_max(getheight(node.getright()),getheight(node.getleft())) + 1
node.setheight(h1)
h2 = my_max(getheight(ret.getright()),getheight(ret.getleft())) + 1
ret.setheight(h2)
return ret
def rightrotation(node):
'''
a mirror symmetry rotation of the leftrotation
'''
print("right rotation node:",node.getdata())
ret = node.getright()
node.setright(ret.getleft())
ret.setleft(node)
h1 = my_max(getheight(node.getright()),getheight(node.getleft())) + 1
node.setheight(h1)
h2 = my_max(getheight(ret.getright()),getheight(ret.getleft())) + 1
ret.setheight(h2)
return ret
def rlrotation(node):
r'''
A A Br
/ \ / \ / \
B C RR Br C LR B A
/ \ --> / \ --> / / \
Bl Br B UB Bl UB C
\ /
UB Bl
RR = rightrotation LR = leftrotation
'''
node.setleft(rightrotation(node.getleft()))
return leftrotation(node)
def lrrotation(node):
node.setright(leftrotation(node.getright()))
return rightrotation(node)
def insert_node(node,data):
if node is None:
return my_node(data)
if data < node.getdata():
node.setleft(insert_node(node.getleft(),data))
if getheight(node.getleft()) - getheight(node.getright()) == 2: #an unbalance detected
if data < node.getleft().getdata(): #new node is the left child of the left child
node = leftrotation(node)
else:
node = rlrotation(node) #new node is the right child of the left child
else:
node.setright(insert_node(node.getright(),data))
if getheight(node.getright()) - getheight(node.getleft()) == 2:
if data < node.getright().getdata():
node = lrrotation(node)
else:
node = rightrotation(node)
h1 = my_max(getheight(node.getright()),getheight(node.getleft())) + 1
node.setheight(h1)
return node
def getRightMost(root):
while root.getright() is not None:
root = root.getright()
return root.getdata()
def getLeftMost(root):
while root.getleft() is not None:
root = root.getleft()
return root.getdata()
def del_node(root,data):
if root.getdata() == data:
if root.getleft() is not None and root.getright() is not None:
temp_data = getLeftMost(root.getright())
root.setdata(temp_data)
root.setright(del_node(root.getright(),temp_data))
elif root.getleft() is not None:
root = root.getleft()
else:
root = root.getright()
elif root.getdata() > data:
if root.getleft() is None:
print("No such data")
return root
else:
root.setleft(del_node(root.getleft(),data))
elif root.getdata() < data:
if root.getright() is None:
return root
else:
root.setright(del_node(root.getright(),data))
if root is None:
return root
if getheight(root.getright()) - getheight(root.getleft()) == 2:
if getheight(root.getright().getright()) > getheight(root.getright().getleft()):
root = rightrotation(root)
else:
root = lrrotation(root)
elif getheight(root.getright()) - getheight(root.getleft()) == -2:
if getheight(root.getleft().getleft()) > getheight(root.getleft().getright()):
root = leftrotation(root)
else:
root = rlrotation(root)
height = my_max(getheight(root.getright()),getheight(root.getleft())) + 1
root.setheight(height)
return root
class AVLtree:
def __init__(self):
self.root = None
def getheight(self):
# print("yyy")
return getheight(self.root)
def insert(self,data):
print("insert:"+str(data))
self.root = insert_node(self.root,data)
def del_node(self,data):
print("delete:"+str(data))
if self.root is None:
print("Tree is empty!")
return
self.root = del_node(self.root,data)
def traversale(self): #a level traversale, gives a more intuitive look on the tree
q = my_queue()
q.push(self.root)
layer = self.getheight()
if layer == 0:
return
cnt = 0
while not q.isEmpty():
node = q.pop()
space = " "*int(math.pow(2,layer-1))
print(space,end = "")
if node is None:
print("*",end = "")
q.push(None)
q.push(None)
else:
print(node.getdata(),end = "")
q.push(node.getleft())
q.push(node.getright())
print(space,end = "")
cnt = cnt + 1
for i in range(100):
if cnt == math.pow(2,i) - 1:
layer = layer -1
if layer == 0:
print()
print("*************************************")
return
print()
break
print()
print("*************************************")
return
def test(self):
getheight(None)
print("****")
self.getheight()
if __name__ == "__main__":
t = AVLtree()
t.traversale()
l = list(range(10))
random.shuffle(l)
for i in l:
t.insert(i)
t.traversale()
random.shuffle(l)
for i in l:
t.del_node(i)
t.traversale()