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Fine tune

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This commit is contained in:
Yudong Jin
2022-12-27 19:24:43 +08:00
parent c4d32621c3
commit dbb25003ec
5 changed files with 7 additions and 30 deletions
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18
codes/python/chapter_tree/avl_tree.py
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@ -16,7 +16,6 @@ class AVLTree:
self.root = root
""" 获取结点高度 """
def height(self, node: typing.Optional[TreeNode]) -> int:
# 空结点高度为 -1 ，叶结点高度为 0
if node is not None:
@ -24,13 +23,11 @@ class AVLTree:
return -1
""" 更新结点高度 """
def __update_height(self, node: TreeNode):
# 结点高度等于最高子树高度 + 1
node.height = max([self.height(node.left), self.height(node.right)]) + 1
""" 获取平衡因子 """
def balance_factor(self, node: TreeNode) -> int:
# 空结点平衡因子为 0
if node is None:
@ -39,7 +36,6 @@ class AVLTree:
return self.height(node.left) - self.height(node.right)
""" 右旋操作 """
def __right_rotate(self, node: TreeNode) -> TreeNode:
child = node.left
grand_child = child.right
@ -53,7 +49,6 @@ class AVLTree:
return child
""" 左旋操作 """
def __left_rotate(self, node: TreeNode) -> TreeNode:
child = node.right
grand_child = child.left
@ -67,7 +62,6 @@ class AVLTree:
return child
""" 执行旋转操作，使该子树重新恢复平衡 """
def __rotate(self, node: TreeNode) -> TreeNode:
# 获取结点 node 的平衡因子
balance_factor = self.balance_factor(node)
@ -93,13 +87,11 @@ class AVLTree:
return node
""" 插入结点 """
def insert(self, val) -> TreeNode:
self.root = self.__insert_helper(self.root, val)
return self.root
""" 递归插入结点（辅助函数）"""
def __insert_helper(self, node: typing.Optional[TreeNode], val: int) -> TreeNode:
if node is None:
return TreeNode(val)
@ -117,13 +109,11 @@ class AVLTree:
return self.__rotate(node)
""" 删除结点 """
def remove(self, val: int):
root = self.__remove_helper(self.root, val)
return root
""" 递归删除结点（辅助函数） """
def __remove_helper(self, node: typing.Optional[TreeNode], val: int) -> typing.Optional[TreeNode]:
if node is None:
return None
@ -142,7 +132,7 @@ class AVLTree:
else:
node = child
else: # 子结点数量 = 2 ，则将中序遍历的下个结点删除，并用该结点替换当前结点
temp = self.min_node(node.right)
temp = self.__min_node(node.right)
node.right = self.__remove_helper(node.right, temp.val)
node.val = temp.val
# 更新结点高度
@ -151,8 +141,7 @@ class AVLTree:
return self.__rotate(node)
""" 获取最小结点 """
def min_node(self, node: typing.Optional[TreeNode]) -> typing.Optional[TreeNode]:
def __min_node(self, node: typing.Optional[TreeNode]) -> typing.Optional[TreeNode]:
if node is None:
return None
# 循环访问左子结点，直到叶结点时为最小结点，跳出
@ -161,7 +150,6 @@ class AVLTree:
return node
""" 查找结点 """
def search(self, val: int):
cur = self.root
# 循环查找，越过叶结点后跳出
@ -179,8 +167,8 @@ class AVLTree:
return cur
""" Driver Code """
if __name__ == "__main__":
def test_insert(tree: AVLTree, val: int):
tree.insert(val)
print("\n插入结点 {} 后，AVL 树为".format(val))