add type hints for avl_tree (#4214)

Co-authored-by: LiHao <leo_how@163.com>

data_structures/binary_tree/avl_tree.py

@@ -8,84 +8,85 @@ python avl_tree.py
 
 import math
 import random
+from typing import Any, List, Optional
 
 
 class my_queue:
-    def __init__(self):
+    def __init__(self) -> None:
-        self.data = []
+        self.data: List[Any] = []
-        self.head = 0
+        self.head: int = 0
-        self.tail = 0
+        self.tail: int = 0
 
-    def is_empty(self):
+    def is_empty(self) -> bool:
         return self.head == self.tail
 
-    def push(self, data):
+    def push(self, data: Any) -> None:
         self.data.append(data)
         self.tail = self.tail + 1
 
-    def pop(self):
+    def pop(self) -> Any:
         ret = self.data[self.head]
         self.head = self.head + 1
         return ret
 
-    def count(self):
+    def count(self) -> int:
         return self.tail - self.head
 
-    def print(self):
+    def print(self) -> None:
         print(self.data)
         print("**************")
         print(self.data[self.head : self.tail])
 
 
 class my_node:
-    def __init__(self, data):
+    def __init__(self, data: Any) -> None:
         self.data = data
-        self.left = None
+        self.left: Optional[my_node] = None
-        self.right = None
+        self.right: Optional[my_node] = None
-        self.height = 1
+        self.height: int = 1
 
-    def get_data(self):
+    def get_data(self) -> Any:
         return self.data
 
-    def get_left(self):
+    def get_left(self) -> Optional["my_node"]:
         return self.left
 
-    def get_right(self):
+    def get_right(self) -> Optional["my_node"]:
         return self.right
 
-    def get_height(self):
+    def get_height(self) -> int:
         return self.height
 
-    def set_data(self, data):
+    def set_data(self, data: Any) -> None:
         self.data = data
         return
 
-    def set_left(self, node):
+    def set_left(self, node: Optional["my_node"]) -> None:
         self.left = node
         return
 
-    def set_right(self, node):
+    def set_right(self, node: Optional["my_node"]) -> None:
         self.right = node
         return
 
-    def set_height(self, height):
+    def set_height(self, height: int) -> None:
         self.height = height
         return
 
 
-def get_height(node):
+def get_height(node: Optional["my_node"]) -> int:
     if node is None:
         return 0
     return node.get_height()
 
 
-def my_max(a, b):
+def my_max(a: int, b: int) -> int:
     if a > b:
         return a
     return b
 
 
-def right_rotation(node):
+def right_rotation(node: my_node) -> my_node:
     r"""
             A                      B
            / \                    / \
@@ -98,6 +99,7 @@ def right_rotation(node):
     """
     print("left rotation node:", node.get_data())
     ret = node.get_left()
+    assert ret is not None
     node.set_left(ret.get_right())
     ret.set_right(node)
     h1 = my_max(get_height(node.get_right()), get_height(node.get_left())) + 1
@@ -107,12 +109,13 @@ def right_rotation(node):
     return ret
 
 
-def left_rotation(node):
+def left_rotation(node: my_node) -> my_node:
     """
     a mirror symmetry rotation of the left_rotation
     """
     print("right rotation node:", node.get_data())
     ret = node.get_right()
+    assert ret is not None
     node.set_right(ret.get_left())
     ret.set_left(node)
     h1 = my_max(get_height(node.get_right()), get_height(node.get_left())) + 1
@@ -122,7 +125,7 @@ def left_rotation(node):
     return ret
 
 
-def lr_rotation(node):
+def lr_rotation(node: my_node) -> my_node:
     r"""
             A              A                    Br
            / \            / \                  /  \
@@ -133,16 +136,20 @@ def lr_rotation(node):
              UB     Bl
     RR = right_rotation   LR = left_rotation
     """
-    node.set_left(left_rotation(node.get_left()))
+    left_child = node.get_left()
+    assert left_child is not None
+    node.set_left(left_rotation(left_child))
     return right_rotation(node)
 
 
-def rl_rotation(node):
+def rl_rotation(node: my_node) -> my_node:
-    node.set_right(right_rotation(node.get_right()))
+    right_child = node.get_right()
+    assert right_child is not None
+    node.set_right(right_rotation(right_child))
     return left_rotation(node)
 
 
-def insert_node(node, data):
+def insert_node(node: Optional["my_node"], data: Any) -> Optional["my_node"]:
     if node is None:
         return my_node(data)
     if data < node.get_data():
@@ -150,8 +157,10 @@ def insert_node(node, data):
         if (
             get_height(node.get_left()) - get_height(node.get_right()) == 2
         ):  # an unbalance detected
+            left_child = node.get_left()
+            assert left_child is not None
             if (
-                data < node.get_left().get_data()
+                data < left_child.get_data()
             ):  # new node is the left child of the left child
                 node = right_rotation(node)
             else:
@@ -159,7 +168,9 @@ def insert_node(node, data):
     else:
         node.set_right(insert_node(node.get_right(), data))
         if get_height(node.get_right()) - get_height(node.get_left()) == 2:
-            if data < node.get_right().get_data():
+            right_child = node.get_right()
+            assert right_child is not None
+            if data < right_child.get_data():
                 node = rl_rotation(node)
             else:
                 node = left_rotation(node)
@@ -168,52 +179,59 @@ def insert_node(node, data):
     return node
 
 
-def get_rightMost(root):
+def get_rightMost(root: my_node) -> Any:
-    while root.get_right() is not None:
+    while True:
-        root = root.get_right()
+        right_child = root.get_right()
+        if right_child is None:
+            break
+        root = right_child
     return root.get_data()
 
 
-def get_leftMost(root):
+def get_leftMost(root: my_node) -> Any:
-    while root.get_left() is not None:
+    while True:
-        root = root.get_left()
+        left_child = root.get_left()
+        if left_child is None:
+            break
+        root = left_child
     return root.get_data()
 
 
-def del_node(root, data):
+def del_node(root: my_node, data: Any) -> Optional["my_node"]:
+    left_child = root.get_left()
+    right_child = root.get_right()
     if root.get_data() == data:
-        if root.get_left() is not None and root.get_right() is not None:
+        if left_child is not None and right_child is not None:
-            temp_data = get_leftMost(root.get_right())
+            temp_data = get_leftMost(right_child)
             root.set_data(temp_data)
-            root.set_right(del_node(root.get_right(), temp_data))
+            root.set_right(del_node(right_child, temp_data))
-        elif root.get_left() is not None:
+        elif left_child is not None:
-            root = root.get_left()
+            root = left_child
+        elif right_child is not None:
+            root = right_child
         else:
-            root = root.get_right()
+            return None
     elif root.get_data() > data:
-        if root.get_left() is None:
+        if left_child is None:
             print("No such data")
             return root
         else:
-            root.set_left(del_node(root.get_left(), data))
+            root.set_left(del_node(left_child, data))
-    elif root.get_data() < data:
+    else:  # root.get_data() < data
-        if root.get_right() is None:
+        if right_child is None:
             return root
         else:
-            root.set_right(del_node(root.get_right(), data))
+            root.set_right(del_node(right_child, data))
-    if root is None:
+
-        return root
+    if get_height(right_child) - get_height(left_child) == 2:
-    if get_height(root.get_right()) - get_height(root.get_left()) == 2:
+        assert right_child is not None
-        if get_height(root.get_right().get_right()) > get_height(
+        if get_height(right_child.get_right()) > get_height(right_child.get_left()):
-            root.get_right().get_left()
-        ):
             root = left_rotation(root)
         else:
             root = rl_rotation(root)
-    elif get_height(root.get_right()) - get_height(root.get_left()) == -2:
+    elif get_height(right_child) - get_height(left_child) == -2:
-        if get_height(root.get_left().get_left()) > get_height(
+        assert left_child is not None
-            root.get_left().get_right()
+        if get_height(left_child.get_left()) > get_height(left_child.get_right()):
-        ):
             root = right_rotation(root)
         else:
             root = lr_rotation(root)
@@ -256,25 +274,26 @@ class AVLtree:
     *************************************
     """
 
-    def __init__(self):
+    def __init__(self) -> None:
-        self.root = None
+        self.root: Optional[my_node] = None
 
-    def get_height(self):
+    def get_height(self) -> int:
-        #        print("yyy")
         return get_height(self.root)
 
-    def insert(self, data):
+    def insert(self, data: Any) -> None:
         print("insert:" + str(data))
         self.root = insert_node(self.root, data)
 
-    def del_node(self, data):
+    def del_node(self, data: Any) -> None:
         print("delete:" + str(data))
         if self.root is None:
             print("Tree is empty!")
             return
         self.root = del_node(self.root, data)
 
-    def __str__(self):  # a level traversale, gives a more intuitive look on the tree
+    def __str__(
+        self,
+    ) -> str:  # a level traversale, gives a more intuitive look on the tree
         output = ""
         q = my_queue()
         q.push(self.root)
@@ -308,7 +327,7 @@ class AVLtree:
         return output
 
 
-def _test():
+def _test() -> None:
     import doctest
 
     doctest.testmod()