From 9d373596a1994b41dc7c8e0d2a73b47a8fdb1ee7 Mon Sep 17 00:00:00 2001
From: Stefan Harmuth <stefan.harmuth@docomodigital.com>
Date: Sun, 16 Jan 2022 17:39:37 +0100
Subject: [PATCH] binary trees; slow af, but functional :D

---
 btree_test.py  |  55 +++++++++
 tools/lists.py |  29 ++++-
 tools/trees.py | 300 ++++++++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 353 insertions(+), 31 deletions(-)
 create mode 100644 btree_test.py

diff --git a/btree_test.py b/btree_test.py
new file mode 100644
index 0000000..ed5c261
--- /dev/null
+++ b/btree_test.py
@@ -0,0 +1,55 @@
+from heapq import heappop, heappush
+from tools.trees import MinHeap, BinarySearchTree
+from tools.stopwatch import StopWatch
+
+
+b = BinarySearchTree()
+for x in range(16):
+    b.add(x)
+b.print()
+print("---")
+b.remove(7)
+b.remove(6)
+b.remove(4)
+b.remove(5)
+b.print()
+
+exit()
+
+# timing below :'-(
+
+s = StopWatch()
+h = []
+for x in range(10_000):
+    heappush(h, x)
+print("Heappush:", s.elapsed())
+while h:
+    heappop(h)
+print("Heappop:", s.elapsed())
+
+s = StopWatch()
+h = MinHeap()
+for x in range(10_000):
+    h.add(x)
+print("MinHeap.add():", s.elapsed())
+while not h.empty():
+    h.pop()
+print("MinHeap.pop():", s.elapsed())
+
+s = StopWatch()
+b = set()
+for x in range(1_000_000):
+    b.add(x)
+print("set.add():", s.elapsed())
+for x in range(1_000_000):
+    _ = x in b
+print("x in set:", s.elapsed())
+
+s = StopWatch()
+b = BinarySearchTree()
+for x in range(1_000_000):
+    b.add(x)
+print("AVL.add():", s.elapsed())
+for x in range(1_000_000):
+    _ = x in b
+print("x in AVL:", s.elapsed())
diff --git a/tools/lists.py b/tools/lists.py
index cb90fde..047a803 100644
--- a/tools/lists.py
+++ b/tools/lists.py
@@ -14,6 +14,25 @@ class LinkedList:
     _tail: Union[Node, None] = None
     size: int = 0
 
+    def _get_head(self):
+        return self._head
+
+    def _get_tail(self):
+        return self._tail
+
+    def _set_head(self, node: Node):
+        node.next = self._head
+        self._head.prev = node
+        self._head = node
+
+    def _set_tail(self, node: Node):
+        node.prev = self._tail
+        self._tail.next = node
+        self._tail = node
+
+    head = property(_get_head, _set_head)
+    tail = property(_get_tail, _set_tail)
+
     def _append(self, obj: Any):
         node = Node(obj)
         if self._head is None:
@@ -110,9 +129,9 @@ class LinkedList:
         return x.value == obj
 
     def __add__(self, other: 'LinkedList') -> 'LinkedList':
-        self._tail.next = other._head
-        other._head.prev = self._tail
-        self._tail = other._tail
+        self._tail.next = other.head
+        other.head.prev = self._tail
+        self._tail = other.tail
         self.size += other.size
         return self
 
@@ -161,5 +180,5 @@ class Queue(LinkedList):
     def peek(self) -> Any:
         return self._head.value
 
-    push = enqueue
-    pop = dequeue
+    push = put = enqueue
+    pop = get = dequeue
diff --git a/tools/trees.py b/tools/trees.py
index 513b1bc..af6f565 100644
--- a/tools/trees.py
+++ b/tools/trees.py
@@ -1,39 +1,287 @@
+from dataclasses import dataclass
+from enum import Enum
+from tools.lists import Queue
 from typing import Any, Union
 
 
-class BinaryTreeNode:
-    data: Any
-    left: Union['BinaryTreeNode', None]
-    right: Union['BinaryTreeNode', None]
+class Rotate(Enum):
+    LEFT = 0
+    RIGHT = 1
 
-    def __init__(self, data: Any):
-        self.data = data
-        self.left = None
-        self.right = None
 
-    def traverse_inorder(self):
-        if self.left:
-            self.left.traverse_inorder()
+@dataclass
+class TreeNode:
+    value: Any
+    parent: Union['TreeNode', None] = None
+    left: Union['TreeNode', None] = None
+    right: Union['TreeNode', None] = None
+    balance_factor: int = 0
+    height: int = 0
 
-        yield self.data
+    def __str__(self):
+        return "TreeNode:(%s; bf: %d, d: %d, p: %s, l: %s, r: %s)" \
+            % (self.value, self.balance_factor, self.height,
+               self.parent.value if self.parent else "None",
+               self.left.value if self.left else "None",
+               self.right.value if self.right else "None")
 
-        if self.right:
-            self.right.traverse_inorder()
+    def __repr__(self):
+        return str(self)
 
-    def traverse_preorder(self):
-        yield self.data
 
-        if self.left:
-            self.left.traverse_preorder()
+def update_node(node: TreeNode):
+    left_depth = node.left.height if node.left is not None else -1
+    right_depth = node.right.height if node.right is not None else -1
+    node.height = 1 + max(left_depth, right_depth)
+    node.balance_factor = right_depth - left_depth
 
-        if self.right:
-            self.right.traverse_preorder()
 
-    def traverse_postorder(self):
-        if self.left:
-            self.left.traverse_preorder()
+class BinarySearchTree:
+    root: Union[TreeNode, None] = None
+    node_count: int = 0
 
-        if self.right:
-            self.right.traverse_postorder()
+    def _balance(self, node: TreeNode) -> TreeNode:
+        if node.balance_factor == -2:
+            if node.left.balance_factor <= 0:
+                return self.rotate(Rotate.RIGHT, node)
+            else:
+                return self.rotate(Rotate.RIGHT, self.rotate(Rotate.LEFT, node.left))
+        elif node.balance_factor == 2:
+            if node.right.balance_factor >= 0:
+                return self.rotate(Rotate.LEFT, node)
+            else:
+                return self.rotate(Rotate.LEFT, self.rotate(Rotate.RIGHT, node.right))
+        else:
+            return node
 
-        yield self.data
+    def _insert(self, node: TreeNode, parent: TreeNode, obj: Any) -> TreeNode:
+        if node is None:
+            return TreeNode(obj, parent)
+
+        if obj < node.value:
+            node.left = self._insert(node.left, node, obj)
+        else:
+            node.right = self._insert(node.right, node, obj)
+
+        update_node(node)
+        return self._balance(node)
+
+    def add(self, obj: Any):
+        if obj is None or obj in self:
+            raise ValueError("obj is None or already present in tree")
+
+        self.root = self._insert(self.root, self.root, obj)
+        self.node_count += 1
+
+    def remove(self, obj: Any, root_node: TreeNode = None):
+        if self.root is None:
+            raise IndexError("remove from empty tree")
+        if root_node is None:
+            root_node = self.root
+
+        node = root_node
+        while node is not None:
+            if obj < node.value:
+                node = node.left
+                continue
+            elif obj > node.value:
+                node = node.right
+                continue
+            else:
+                if node.left is None and node.right is None:  # leaf node
+                    if node.parent is not None:
+                        if node.parent.left == node:
+                            node.parent.left = None
+                        else:
+                            node.parent.right = None
+                elif node.left is not None and node.right is not None:  # both subtrees present
+                    d_node = node.left
+                    while d_node.right is not None:
+                        d_node = d_node.right
+                    node.value = d_node.value
+                    self.remove(node.value, d_node)
+                elif node.left is None:  # only a subtree on the right
+                    if node.parent is not None:
+                        if node.parent.left == node:
+                            node.parent.left = node.right
+                        else:
+                            node.parent.right = node.right
+                    node.right.parent = node.parent
+                else:  # only a subtree on the left
+                    if node.parent is not None:
+                        if node.parent.left == node:
+                            node.parent.left = node.left
+                        else:
+                            node.parent.right = node.left
+                    node.left.parent = node.parent
+
+                update_node(root_node)
+                self._balance(root_node)
+                return
+
+        raise ValueError("obj not in tree:", obj)
+
+    def rotate(self, direction: Rotate, node: TreeNode = None) -> TreeNode:
+        if node is None:
+            node = self.root
+
+        parent = node.parent
+        if direction == Rotate.LEFT:
+            pivot = node.right
+            node.right = pivot.left
+            if pivot.left is not None:
+                pivot.left.parent = node
+            pivot.left = node
+        else:
+            pivot = node.left
+            node.left = pivot.right
+            if pivot.right is not None:
+                pivot.right.parent = node
+            pivot.right = node
+
+        node.parent = pivot
+        pivot.parent = parent
+
+        if parent is not None:
+            if parent.left == node:
+                parent.left = pivot
+            else:
+                parent.right = pivot
+
+        if node == self.root:
+            self.root = pivot
+
+        update_node(node)
+        update_node(pivot)
+
+        return pivot
+
+    def print(self, node: TreeNode = None, level: int = 0):
+        if node is None:
+            if level == 0 and self.root is not None:
+                node = self.root
+            else:
+                return
+
+        self.print(node.right, level + 1)
+        print(" " * 4 * level + '->', node)
+        self.print(node.left, level + 1)
+
+    def __contains__(self, obj: Any) -> bool:
+        if self.root is None:
+            return False
+
+        c_node = self.root
+        while c_node is not None:
+            if obj == c_node.value:
+                return True
+            elif obj < c_node.value:
+                c_node = c_node.left
+            else:
+                c_node = c_node.right
+
+        return False
+
+    def __len__(self) -> int:
+        return self.node_count
+
+
+class Heap(BinarySearchTree):
+    def _find_left(self) -> TreeNode:
+        heap = Queue()
+        heap.put(self.root)
+        while c_node := heap.get():
+            if c_node.left is None or c_node.right is None:
+                return c_node
+            else:
+                heap.put(c_node.left)
+                heap.put(c_node.right)
+
+    def _find_right(self) -> TreeNode:
+        heap = [self.root]
+        while c_node := heap.pop():
+            if c_node.left is None and c_node.right is None:
+                return c_node
+            else:
+                if c_node.left is not None:
+                    heap.append(c_node.left)
+                if c_node.right is not None:
+                    heap.append(c_node.right)
+
+    def _sort_up(self, node: TreeNode):
+        pass
+
+    def _heapify(self):
+        pass
+
+    def empty(self) -> bool:
+        return self.root is None
+
+    def add(self, obj: Any):
+        node = TreeNode(obj)
+        if self.root is None:
+            self.root = node
+        else:
+            t_node = self._find_left()
+            if t_node.left is None:
+                t_node.left = node
+            else:
+                t_node.right = node
+            node.parent = t_node
+            self._sort_up(node)
+
+    def pop(self) -> Any:
+        if self.root is None:
+            raise IndexError("pop from empty heap")
+
+        ret = self.root.value
+        if self.root.left is None and self.root.right is None:
+            self.root = None
+        else:
+            d_node = self._find_right()
+            self.root.value = d_node.value
+            if d_node.parent.left == d_node:
+                d_node.parent.left = None
+            else:
+                d_node.parent.right = None
+            self._heapify()
+
+        return ret
+
+
+class MinHeap(Heap):
+    def _sort_up(self, node: TreeNode):
+        while node.parent is not None and node.value < node.parent.value:
+            node.value, node.parent.value = node.parent.value, node.value
+            node = node.parent
+
+    def _heapify(self):
+        node = self.root
+        while node is not None:
+            if node.left and node.left.value < node.value and (not node.right or node.right.value > node.left.value):
+                node.left.value, node.value = node.value, node.left.value
+                node = node.left
+            elif node.right and node.right.value < node.value and (not node.left or node.left.value > node.right.value):
+                node.right.value, node.value = node.value, node.right.value
+                node = node.right
+            else:
+                break
+
+
+class MaxHeap(Heap):
+    def _sort_up(self, node: TreeNode):
+        while node.parent is not None and node.value > node.parent.value:
+            node.value, node.parent.value = node.parent.value, node.value
+            node = node.parent
+
+    def _heapify(self):
+        node = self.root
+        while node is not None:
+            if node.left and node.left.value > node.value and (not node.right or node.right.value < node.left.value):
+                node.left.value, node.value = node.value, node.left.value
+                node = node.left
+            elif node.right and node.right.value > node.value and (not node.left or node.left.value < node.right.value):
+                node.right.value, node.value = node.value, node.right.value
+                node = node.right
+            else:
+                break