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RedBlackTree.py
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import sys
class Node:
def __init__(self,data):
self.data=data
self.left=None
self.right=None
self.color=1 #red
self.parent=None
class redblacktree:
def __init__(self):
self.null= Node(0)#nil
self.null.right=None
self.null.left=None
self.null.color=0 #black
self.root=self.null
def inorder(self):
return self.__inorder(self.root)
def __inorder(self,node):
if node!= null:
self.__inorder(node.left)
print(node.data)
self.__inorder(node.right)
#wrapper function
def search(self,k):
return self.__search(self.root,k)
#searching for the node in BST
def __search(self,node,key):
if node == null and key == node.data:
return node
if key < node.data:
return self.__search(node.left,key)
return self.__search(node.right,key)
#inserting nodes
def insert(self,key):
node=Node(key)
node.parent=None
node.right=self.null
node.left=self.null
node.data=key
node.color=1 #red
y=None #(y=leaf)
x= self.root
#y=None #(y=leaf)
while x!=self.null:
y=x
if node.data< x.data:
x=x.left
else:
x=x.right
node.parent=y
if y== None:
self.root=node
elif node.data<y.data:
y.left=node
else:
y.right=node
if node.parent==None:
node.color=0
return
if node.parent.parent == None:
return
self.__node_insertion(node)
def __node_insertion(self,k):
while k.parent.color==1:
if k.parent==k.parent.parent.right:
u=k.parent.parent.left
if u.color==1:
u.color=0
k.parent.color = 0
k.parent.parent.color=1
k=k.parent.parent
else:
if k==k.parent.parent.left:
#assign parernt to the newnode
k=k.parent
self.right_rotate(k)
k.parent.color=0
k.parent.parent.color=1
self.left_rotate(k.parent.parent)
else:
u=k.parent.parent.right
if u.color==1:
u.color=0
k.parent.color=0
k.parent.parent.color=1
k=k.parent.parent
else:
if k==k.parent.parent.right:
k=k.parent
self.left_rotate(k)
k.parent.color=0
k.parent.parent.color=1
self.right_rotate(k.parent.parent)
if k==self.root:
break
self.root.color = 0
def left_rotate(self,x):
y=x.right
x.right=y.left
if y.left != self.null:
y.left.parent=x
y.parent=x.parent
if x.parent == None:
self.root = y
elif (x==x.parent.left):
x.parent.left=y
else:
x.parent.right=y
y.left=x
x.parent=y
def right_rotate(self,x):
y = x.left
x.left = y.right
if y.right != self.null:
y.right.parent = x
y.parent = x.parent
if x.parent == None:
self.root = y
elif x == x.parent.right:
x.parent.right = y
else:
x.parent.left = y
y.right = x
x.parent = y
def __ptree(self, node, indent, last):
if node.color==1:
s_color="RED"
else:
s_color="BLACK"
if node != self.null:
print(indent)
if last:
#indent +=" "
print(indent,"R----",str(node.data) + "(" + s_color + ")")
indent += " "
else:
print(indent,"L----",str(node.data) + "(" + s_color + ")")
indent += " "
self.__ptree(node.left, indent, False)
self.__ptree(node.right, indent, True)
def print(self):
self.__ptree(self.root, "", True)
def after_delete_prop(self,x):
while x != self.root and x.color == 0:
if x == x.parent.left:
s = x.parent.right
if s.color == 1:
s.color = 0
x.parent.color = 1
self.left_rotate(x.parent)
s = x.parent.right
if s.left.color == 0 and s.right.color == 0:
s.color = 1
x = x.parent
else:
if s.right.color == 0:
s.left.color = 0
s.color = 1
self.right_rotate(s)
s = x.parent.right
s.color = x.parent.color
x.parent.color = 0
s.right.color = 0
self.left_rotate(x.parent)
x = self.root
else:
s = x.parent.left
if s.color == 1:
s.color = 0
x.parent.color = 1
self.right_rotate(x.parent)
s = x.parent.left
if s.right.color == 0 and s.right.color == 0:
s.color = 1
x = x.parent
else:
if s.left.color == 0:
s.right.color = 0
s.color = 1
self.left_rotate(s)
s = x.parent.left
s.color = x.parent.color
x.parent.color = 0
s.left.color = 0
self.right_rotate(x.parent)
x = self.root
x.color = 0
#delete node (case1) deletion of rednode
def __delete_node(self,node,key):
z=self.null
while node != self.null:
if node.data==key:
z=node
if node.data<=key:
node=node.right
else:
node=node.left
if z==self.null:
print("tree me value nai ha")
return
y=z
y_node_color=y.color
if z.left == self.null:
x=z.right
self.__exchange_fromnodetobedeleted(z, z.right)
elif z.right==self.null:
x=z.left
self.__exchange_fromnodetobedeleted(z, z.left)
else:
y=self.minimum_value(z.right)
y_node_color=y.color
x=y.right
if y.parent == z:
x.parent = y
else:
self.__exchange_fromnodetobedeleted(y, y.right)
y.right = z.right
y.right.parent = y
self.__exchange_fromnodetobedeleted(z,y)
y.left = z.left
y.left.parent = y
y.color = z.color
if y_node_color == 0:
self.after_delete_prop(x)
def __exchange_fromnodetobedeleted(self,node1,node2):
if node1.parent==None:
self.root=node2
elif node1 == node1.parent.left:
node1.parent.left =node2
else:
node1.parent.right =node2
node2.parent = node1.parent
def minimum_value(self,node):
while(node.left != None):
node = node.left
return node
def deletenode(self, data):
self.__delete_node(self.root,data)
def successor(self, x):
if x.right != self.null:
return self.minimum_value(x.right)
y = x.parent
while y != self.null and x == y.right:
x = y
y = y.parent
#driver code
ob=redblacktree()
print("___________left leaning red black tree_________")
print(" __________INSERTION__________")
ob.insert(55)
ob.insert(40)
ob.insert(30)
ob.insert(35)
ob.insert(25)
ob.insert(6)
ob.print()
print(" ______________AFTER DELETION_____________")
ob.deletenode(25)
ob.print()