165 lines
4.6 KiB
Python
165 lines
4.6 KiB
Python
from avl import AVLTree
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from node import Node, NodeType, Comparable, RotateFunction
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import logging
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from typing import TypeVar, Optional
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logger = logging.getLogger(__name__)
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T = TypeVar("T", bound=Comparable)
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class WAVLTree(AVLTree[T]):
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def is_correct_node(
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self, node: Optional[Node[T]], recursive: bool = True
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) -> bool:
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if not node:
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return True
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for child_rank in Node.differences(node):
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if child_rank not in (1, 2):
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return False
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if node.type == NodeType.LEAF:
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return node.rank == 0
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return not recursive or (
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self.is_correct_node(node.left)
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and self.is_correct_node(node.right)
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)
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# region DeleteRebalance
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@staticmethod
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def __fix_delete(
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x: Optional[Node[T]],
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y: Node[T],
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z: Node[T],
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reversed: bool,
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rotate_left: RotateFunction[T],
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rotate_right: RotateFunction[T],
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) -> Optional[Node[T]]:
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new_root = x
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v = y.left
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w = y.right
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if reversed:
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v, w = w, v
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logger.debug(f"__fix_delete({x}, {y}, {z}, {reversed})")
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w_diff = Node.difference(w, y)
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logger.debug(f"w_diff = {w_diff}")
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# assert v
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if w_diff == 1 and y.parent:
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logger.debug(f"y.parent = {y.parent}")
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new_root = rotate_left(y.parent)
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y.promote()
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z.demote()
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if z.type == NodeType.LEAF:
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z.demote()
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elif w_diff == 2 and v.parent:
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logger.debug(f"v.parent = {v.parent}")
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rotate_right(v.parent)
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new_root = rotate_left(v.parent)
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v.promote().promote()
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y.demote()
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z.demote().demote()
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return new_root
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def __bottomup_delete(
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self, x: Optional[Node[T]], parent: Optional[Node[T]]
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) -> None:
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x_diff = Node.difference(x, parent)
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if x_diff != 3 or not parent:
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return
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y = parent.right if parent.left is x else parent.left
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y_diff = Node.difference(y, parent)
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while (
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parent
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and x_diff == 3
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and y
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and (y_diff == 2 or Node.differences(y) == (2, 2))
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):
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parent.demote()
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if y_diff != 2:
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y.demote()
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x = parent
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parent = x.parent
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if not parent:
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return
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y = parent.right if parent.left is x else parent.left
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x_diff = Node.difference(x, parent)
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y_diff = Node.difference(y, parent)
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if not parent:
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return
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rotating_around_root = parent.parent is None
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new_root: Optional[Node[T]] = parent
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parent_node_diffs = Node.differences(parent)
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if parent_node_diffs in ((1, 3), (3, 1)):
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if parent.left is x:
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assert parent.right
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new_root = WAVLTree.__fix_delete(
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x,
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parent.right,
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parent,
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False,
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Node.rotate_left,
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Node.rotate_right,
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)
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else:
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assert parent.left
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new_root = WAVLTree.__fix_delete(
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x,
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parent.left,
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parent,
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True,
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Node.rotate_right,
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Node.rotate_left,
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)
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if rotating_around_root:
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self.root = new_root
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def __delete_fixup(
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self, y: Optional[Node[T]], parent: Optional[Node[T]] = None
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) -> None:
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logger.debug(f"[__delete_fixup] y = {y}, parent = {parent}")
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z = y if y else parent
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logger.debug(
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f"[z.demote()] Node.differences({repr(z)}) == (2, 2) ~>*"
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f"{Node.differences(z)} == (2, 2)"
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)
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assert z
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if Node.differences(z) == (2, 2):
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z.demote()
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if parent:
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for y in (parent.left, parent.right):
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logger.debug(
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f"[bottom-up delete] Node.difference({y}, {parent}) == 3"
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f"~>* {Node.difference(y, parent)} == 3"
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)
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if Node.difference(y, parent) == 3:
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self.__bottomup_delete(y, parent)
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def _delete_rebalance(
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self, node: Optional[Node[T]], parent: Optional[Node[T]]
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) -> None:
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while node or parent:
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self.__delete_fixup(node, parent)
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node, parent = parent, (parent.parent if parent else None)
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# endregion DeleteRebalance
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