implemented bst

soninrv/docs/data/lab1/phonebook.py

@@ -89,3 +89,76 @@ def ht_list_all(buckets):
         result.extend(ll_list_all(head))
     result.sort(key=lambda x: x[0])
     return result
+
+# 3. ДВОИЧНОЕ ДЕРЕВО ПОИСКА (BST)
+
+def bst_create_node(name, phone):
+    return {'name': name, 'phone': phone, 'left': None, 'right': None}
+
+
+def bst_insert(root, name, phone):
+    """Вставить / обновить. Возвращает корень."""
+    if root is None:
+        return bst_create_node(name, phone)
+    if name == root['name']:
+        root['phone'] = phone
+    elif name < root['name']:
+        root['left'] = bst_insert(root['left'], name, phone)
+    else:
+        root['right'] = bst_insert(root['right'], name, phone)
+    return root
+
+
+def bst_find(root, name):
+    """Вернуть телефон или None."""
+    while root is not None:
+        if name == root['name']:
+            return root['phone']
+        elif name < root['name']:
+            root = root['left']
+        else:
+            root = root['right']
+    return None
+
+
+def _bst_min(node):
+    while node['left'] is not None:
+        node = node['left']
+    return node
+
+
+def bst_delete(root, name):
+    """Удалить узел, вернуть новый корень."""
+    if root is None:
+        return None
+    if name < root['name']:
+        root['left'] = bst_delete(root['left'], name)
+    elif name > root['name']:
+        root['right'] = bst_delete(root['right'], name)
+    else:
+        # Узел найден
+        if root['left'] is None:
+            return root['right']
+        if root['right'] is None:
+            return root['left']
+        # Два потомка: заменить минимальным из правого поддерева
+        successor = _bst_min(root['right'])
+        root['name'] = successor['name']
+        root['phone'] = successor['phone']
+        root['right'] = bst_delete(root['right'], successor['name'])
+    return root
+
+
+def bst_list_all(root):
+    """Центрированный (in-order) обход → отсортированный список."""
+    result = []
+    stack = []
+    node = root
+    while stack or node is not None:
+        while node is not None:
+            stack.append(node)
+            node = node['left']
+        node = stack.pop()
+        result.append((node['name'], node['phone']))
+        node = node['right']
+    return result