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splay.py
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splay.py
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import sys
class Node():
def __init__(self, key, data=0):
self.key = key
self.data = data
self.left = None
self.right = None
self.parent = None
class Tree():
def __init__(self):
self.root = None
def printr(self, currPtr, indent, last):
# sys.stdout.write the tree structure on the screen
if currPtr != None:
sys.stdout.write(indent)
if last:
sys.stdout.write("R---- ")
indent += " "
else:
sys.stdout.write("L---- ")
indent += "| "
print(f"{currPtr.key}|{currPtr.data}")
self.printr(currPtr.left, indent, False)
self.printr(currPtr.right, indent, True)
def searchr(self, node, key):
if node == None or key == node.key:
return node
if key < node.key:
return self.searchr(node.left, key)
return self.searchr(node.right, key)
def minimum(self, node):
while node.left != None:
node = node.left
return node
def maximum(self, node):
while node.right != None:
node = node.right
return node
def rotr(self, x):
y = x.left
x.left = y.right
if y.right != None:
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 rotl(self, x):
y = x.right
x.right = y.left
if y.left != None:
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 splay(self, x):
while x.parent != None:
if x.parent.parent == None:
if x == x.parent.left:
# zig rotation
self.rotr(x.parent)
else:
# zag rotation
self.rotl(x.parent)
elif x == x.parent.left and x.parent == x.parent.parent.left:
# zig-zig rotation
self.rotr(x.parent.parent)
self.rotr(x.parent)
elif x == x.parent.right and x.parent == x.parent.parent.right:
# zag-zag rotation
self.rotl(x.parent.parent)
self.rotl(x.parent)
elif x == x.parent.right and x.parent == x.parent.parent.left:
# zig-zag rotation
self.rotl(x.parent)
self.rotr(x.parent)
else:
# zag-zig rotation
self.rotr(x.parent)
self.rotl(x.parent)
def search(self, k):
x = self.searchr(self.root, k)
if x != None and x != self.root:
self.splay(x)
return x
def insert(self, *keys):
if type(keys[0]) == list:
for key in keys[0]:
self.insert(key)
return self
for key in keys:
if hasattr(key, "__iter__"):
node = Node(key[0], key[1])
else:
node = Node(key)
y = None
x = self.root
while x != None:
y = x
if node.key < x.key:
x = x.left
elif node.key > x.key:
x = x.right
else: # node with key already exists
x.data = node.data
self.splay(x)
return self
# y is parent of x
node.parent = y
if y == None:
self.root = node
elif node.key < y.key:
y.left = node
else:
y.right = node
# splay the node
self.splay(node)
return self
def print(self):
self.printr(self.root, "", True)