| 1 | 1 | class Zipper: |
| 2 | | # Tree is a dict with keys "value" (int), "left" (dict or None), "right" (dict or None) |
| 2 | def __init__(self, node, path): |
| 3 | # Edge Case: Initialize with None node (should not happen in normal operation but handled for safety) |
| 4 | self._node = node |
| 5 | self._path = path |
| 6 | |
| 3 | 7 | @staticmethod |
| 4 | | def from_tree(tree: dict) -> "Zipper": |
| 5 | | pass |
| 8 | def from_tree(tree): |
| 9 | # Edge Case: Handle None tree input |
| 10 | if tree is None: |
| 11 | return None |
| 12 | return Zipper(tree, []) |
| 13 | |
| 14 | def value(self): |
| 15 | # Edge Case: Access value of None node |
| 16 | if self._node is None: |
| 17 | return None |
| 18 | return self._node["value"] |
| 6 | 19 | |
| 7 | | def value(self) -> int: |
| 8 | | pass |
| 20 | def set_value(self, value): |
| 21 | # Edge Case: Set value on None node |
| 22 | if self._node is None: |
| 23 | return self |
| 24 | new_node = { |
| 25 | "value": value, |
| 26 | "left": self._node["left"], |
| 27 | "right": self._node["right"] |
| 28 | } |
| 29 | return Zipper(new_node, self._path) |
| 9 | 30 | |
| 10 | | def set_value(self, value: int) -> "Zipper": |
| 11 | | pass |
| 31 | def left(self): |
| 32 | # Edge Case: Navigate left from None node |
| 33 | if self._node is None: |
| 34 | return None |
| 35 | left_child = self._node.get("left") |
| 36 | # Edge Case: Left child is None |
| 37 | if left_child is None: |
| 38 | return None |
| 39 | # Create breadcrumb to current node |
| 40 | breadcrumb = { |
| 41 | "parent": self._node, |
| 42 | "side": "left", |
| 43 | "right": self._node["right"] |
| 44 | } |
| 45 | return Zipper(left_child, self._path + [breadcrumb]) |
| 12 | 46 | |
| 13 | | def left(self) -> "Zipper | None": |
| 14 | | pass |
| 47 | def set_left(self, tree): |
| 48 | # Edge Case: Set left on None node |
| 49 | if self._node is None: |
| 50 | return self |
| 51 | new_node = { |
| 52 | "value": self._node["value"], |
| 53 | "left": tree, |
| 54 | "right": self._node["right"] |
| 55 | } |
| 56 | return Zipper(new_node, self._path) |
| 15 | 57 | |
| 16 | | def set_left(self, tree: dict | None) -> "Zipper": |
| 17 | | pass |
| 58 | def right(self): |
| 59 | # Edge Case: Navigate right from None node |
| 60 | if self._node is None: |
| 61 | return None |
| 62 | right_child = self._node.get("right") |
| 63 | # Edge Case: Right child is None |
| 64 | if right_child is None: |
| 65 | return None |
| 66 | # Create breadcrumb to current node |
| 67 | breadcrumb = { |
| 68 | "parent": self._node, |
| 69 | "side": "right", |
| 70 | "left": self._node["left"] |
| 71 | } |
| 72 | return Zipper(right_child, self._path + [breadcrumb]) |
| 18 | 73 | |
| 19 | | def right(self) -> "Zipper | None": |
| 20 | | pass |
| 74 | def set_right(self, tree): |
| 75 | # Edge Case: Set right on None node |
| 76 | if self._node is None: |
| 77 | return self |
| 78 | new_node = { |
| 79 | "value": self._node["value"], |
| 80 | "left": self._node["left"], |
| 81 | "right": tree |
| 82 | } |
| 83 | return Zipper(new_node, self._path) |
| 21 | 84 | |
| 22 | | def set_right(self, tree: dict | None) -> "Zipper": |
| 23 | | pass |
| 85 | def up(self): |
| 86 | # Edge Case: Try to go up from root (no path) |
| 87 | if not self._path: |
| 88 | return None |
| 89 | # Get the last breadcrumb |
| 90 | parent_info = self._path[-1] |
| 91 | parent = parent_info["parent"] |
| 92 | side = parent_info["side"] |
| 93 | |
| 94 | # Reconstruct parent with current node in the correct position |
| 95 | new_parent = parent.copy() |
| 96 | if side == "left": |
| 97 | new_parent["left"] = self._node |
| 98 | new_parent["right"] = parent_info["right"] |
| 99 | else: # side == "right" |
| 100 | new_parent["left"] = parent_info["left"] |
| 101 | new_parent["right"] = self._node |
| 102 | |
| 103 | return Zipper(new_parent, self._path[:-1]) |
| 24 | 104 | |
| 25 | | def up(self) -> "Zipper | None": |
| 26 | | pass |
| 105 | def to_tree(self): |
| 106 | # Navigate up to the root to get the full tree |
| 107 | current = self |
| 108 | while True: |
| 109 | # Edge Case: Current zipper is at root (no parent) |
| 110 | if not current._path: |
| 111 | return current._node |
| 112 | current = current.up() |
| 113 | # Edge Case: Up navigation failed (should not happen with valid path) |
| 114 | if current is None: |
| 115 | return self._node |
| 27 | 116 | |
| 28 | | def to_tree(self) -> dict: |
| 29 | | pass |
| 117 | # Handled Edge Cases: None node initialization, None tree input, accessing/modifying None nodes, navigating from None nodes, navigating when child is None, going up from root, failed up navigation |