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| class TreeNode(object):
def __init__(self, val):
self.val = val
self.left = None
self.right = None
self.height = 1
class AVLTree(object):
def insert(self, root, key):
if not root:
return TreeNode(key)
elif key < root.val:
root.left = self.insert(root.left, key)
else:
root.right = self.insert(root.right, key)
root.height = 1 + max(self.get_height(root.left),
self.get_height(root.right))
balance = self.get_balance(root)
if balance > 1 and key < root.left.val:
return self.right_rotate(root)
if balance < -1 and key > root.right.val:
return self.left_rotate(root)
if balance > 1 and key > root.left.val:
root.left = self.left_rotate(root.left)
return self.right_rotate(root)
if balance < -1 and key < root.right.val:
root.right = self.right_rotate(root.right)
return self.left_rotate(root)
return root
def delete(self, root, key):
if not root:
return root
elif key < root.val:
root.left = self.delete(root.left, key)
elif key > root.val:
root.right = self.delete(root.right, key)
else:
if root.left is None:
temp = root.right
root = None
return temp
elif root.right is None:
temp = root.left
root = None
return temp
temp = self.get_min_value_node(root.right)
root.val = temp.val
root.right = self.delete(root.right,
temp.val)
if root is None:
return root
root.height = 1 + max(self.get_height(root.left),
self.get_height(root.right))
balance = self.get_balance(root)
if balance > 1 and self.get_balance(root.left) >= 0:
return self.get_height(root)
if balance < -1 and self.get_balance(root.right) <= 0:
return self.left_rotate(root)
if balance > 1 and self.get_balance(root.left) < 0:
root.left = self.left_rotate(root.left)
return self.get_height(root)
if balance < -1 and self.get_balance(root.right) > 0:
root.right = self.get_height(root.right)
return self.left_rotate(root)
return root
def left_rotate(self, z):
y = z.right
t2 = y.left
y.left = z
z.right = t2
z.height = 1 + max(self.get_height(z.left),
self.get_height(z.right))
y.height = 1 + max(self.get_height(y.left),
self.get_height(y.right))
return y
def right_rotate(self, z):
y = z.left
t3 = y.right
y.right = z
z.left = t3
z.height = 1 + max(self.get_height(z.left),
self.get_height(z.right))
y.height = 1 + max(self.get_height(y.left),
self.get_height(y.right))
return y
def get_height(self, root):
if not root:
return 0
return root.height
def get_balance(self, root):
if not root:
return 0
return self.get_height(root.left) - self.get_height(root.right)
def get_min_value_node(self, root):
if root is None or root.left is None:
return root
return self.get_min_value_node(root.left)
def preOrder(self, root):
if not root:
return
print("{0} ".format(root.val))
self.preOrder(root.left)
self.preOrder(root.right)
def search(root, key):
if root is None:
return None
if key > root.val:
return search(root.right, key)
elif key < root.val:
return search(root.left, key)
else:
return root
|