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Update AVLtree.py

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This commit is contained in:
Awfifcuihc 2018-11-22 14:33:50 +08:00
parent d1dba51326
commit 9bbc4d9021
1 changed files with 32 additions and 8 deletions
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40
data_structures/binary tree/AVLtree.py
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@ -53,7 +53,6 @@ class my_node:
return return
def getheight(node): def getheight(node):
# print("xxx")
if node is None: if node is None:
return 0 return 0
return node.getheight() return node.getheight()
@ -66,6 +65,17 @@ def my_max(a,b):
def leftrotation(node): def leftrotation(node):
'''
A B
/ \ / \
B C Bl A
/ \ --> / / \
Bl Br UB Br C
/
UB
UB = unbalanced node
'''
print("left rotation node:",node.getdata()) print("left rotation node:",node.getdata())
ret = node.getleft() ret = node.getleft()
node.setleft(ret.getright()) node.setleft(ret.getright())
@ -77,6 +87,9 @@ def leftrotation(node):
return ret return ret
def rightrotation(node): def rightrotation(node):
'''
a mirror symmetry rotation of the leftrotation
'''
print("right rotation node:",node.getdata()) print("right rotation node:",node.getdata())
ret = node.getright() ret = node.getright()
node.setright(ret.getleft()) node.setright(ret.getleft())
@ -87,24 +100,35 @@ def rightrotation(node):
ret.setheight(h2) ret.setheight(h2)
return ret return ret
def rlrotation(node):
'''
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): def lrrotation(node):
node.setright(leftrotation(node.getright())) node.setright(leftrotation(node.getright()))
return rightrotation(node) return rightrotation(node)
def rlrotation(node):
node.setleft(rightrotation(node.getleft()))
return leftrotation(node)
def insert_node(node,data): def insert_node(node,data):
if node is None: if node is None:
return my_node(data) return my_node(data)
if data < node.getdata(): if data < node.getdata():
node.setleft(insert_node(node.getleft(),data)) node.setleft(insert_node(node.getleft(),data))
if getheight(node.getleft()) - getheight(node.getright()) == 2: if getheight(node.getleft()) - getheight(node.getright()) == 2: #an unbalance detected
if data < node.getleft().getdata(): if data < node.getleft().getdata(): #new node is the left child of the left child
node = leftrotation(node) node = leftrotation(node)
else: else:
node = rlrotation(node) node = rlrotation(node) #new node is the right child of the left child
else: else:
node.setright(insert_node(node.getright(),data)) node.setright(insert_node(node.getright(),data))
if getheight(node.getright()) - getheight(node.getleft()) == 2: if getheight(node.getright()) - getheight(node.getleft()) == 2:
@ -178,7 +202,7 @@ class AVLtree:
print("Tree is empty!") print("Tree is empty!")
return return
self.root = del_node(self.root,data) self.root = del_node(self.root,data)
def traversale(self): def traversale(self): #a level traversale, gives a more intuitive look on the tree
q = my_queue() q = my_queue()
q.push(self.root) q.push(self.root)
layer = self.getheight() layer = self.getheight()