| 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, tree, path): |
| 3 | # Initialize a Zipper with a tree and a path |
| 4 | self.tree = tree |
| 5 | self.path = path |
| 6 | |
| 7 | # Edge Case: Handle empty tree when creating zipper from tree |
| 3 | 8 | @staticmethod |
| 4 | 9 | def from_tree(tree: dict) -> "Zipper": |
| 5 | | pass |
| 6 | | |
| 10 | if not tree: |
| 11 | return None |
| 12 | return Zipper(tree, []) |
| 13 | |
| 14 | # Edge Case: Handle when focus node is None |
| 7 | 15 | def value(self) -> int: |
| 8 | | pass |
| 9 | | |
| 16 | if not self.tree: |
| 17 | return None |
| 18 | return self.tree["value"] |
| 19 | |
| 20 | # Edge Case: Handle when setting value on None focus |
| 10 | 21 | def set_value(self, value: int) -> "Zipper": |
| 11 | | pass |
| 12 | | |
| 22 | if not self.tree: |
| 23 | return self |
| 24 | new_tree = self._copy_tree(self.tree) |
| 25 | new_tree["value"] = value |
| 26 | return Zipper(new_tree, self.path[:]) |
| 27 | |
| 28 | # Edge Case: Handle when moving left from None or when no left child exists |
| 13 | 29 | def left(self) -> "Zipper | None": |
| 14 | | pass |
| 15 | | |
| 30 | if not self.tree or not self.tree.get("left"): |
| 31 | return None |
| 32 | new_path = self.path + [(self.tree, "left")] |
| 33 | return Zipper(self.tree["left"], new_path) |
| 34 | |
| 35 | # Edge Case: Handle when setting left child on None focus |
| 16 | 36 | def set_left(self, tree: dict | None) -> "Zipper": |
| 17 | | pass |
| 18 | | |
| 37 | if not self.tree: |
| 38 | return self |
| 39 | new_tree = self._copy_tree(self.tree) |
| 40 | new_tree["left"] = tree |
| 41 | return Zipper(new_tree, self.path[:]) |
| 42 | |
| 43 | # Edge Case: Handle when moving right from None or when no right child exists |
| 19 | 44 | def right(self) -> "Zipper | None": |
| 20 | | pass |
| 21 | | |
| 45 | if not self.tree or not self.tree.get("right"): |
| 46 | return None |
| 47 | new_path = self.path + [(self.tree, "right")] |
| 48 | return Zipper(self.tree["right"], new_path) |
| 49 | |
| 50 | # Edge Case: Handle when setting right child on None focus |
| 22 | 51 | def set_right(self, tree: dict | None) -> "Zipper": |
| 23 | | pass |
| 24 | | |
| 52 | if not self.tree: |
| 53 | return self |
| 54 | new_tree = self._copy_tree(self.tree) |
| 55 | new_tree["right"] = tree |
| 56 | return Zipper(new_tree, self.path[:]) |
| 57 | |
| 58 | # Edge Case: Handle when moving up from root (no parent) |
| 25 | 59 | def up(self) -> "Zipper | None": |
| 26 | | pass |
| 27 | | |
| 60 | if not self.path: |
| 61 | return None |
| 62 | parent, direction = self.path[-1] |
| 63 | new_tree = self._copy_tree(parent) |
| 64 | if direction == "left": |
| 65 | new_tree["left"] = self.tree |
| 66 | else: # direction == "right" |
| 67 | new_tree["right"] = self.tree |
| 68 | return Zipper(new_tree, self.path[:-1]) |
| 69 | |
| 70 | # Edge Case: Handle when converting None tree to tree representation |
| 28 | 71 | def to_tree(self) -> dict: |
| 29 | | pass |
| 72 | if not self.tree: |
| 73 | return None |
| 74 | if not self.path: |
| 75 | return self.tree |
| 76 | # Reconstruct the full tree by going up to the root |
| 77 | current_zipper = self |
| 78 | while True: |
| 79 | parent_zipper = current_zipper.up() |
| 80 | if parent_zipper is None: |
| 81 | return current_zipper.tree |
| 82 | current_zipper = parent_zipper |
| 83 | |
| 84 | def _copy_tree(self, tree): |
| 85 | # Helper method to create a deep copy of a tree |
| 86 | if not tree: |
| 87 | return None |
| 88 | new_tree = { |
| 89 | "value": tree["value"], |
| 90 | "left": self._copy_tree(tree.get("left")), |
| 91 | "right": self._copy_tree(tree.get("right")) |
| 92 | } |
| 93 | return new_tree |
| 94 | |
| 95 | # Handled Edge Cases: Empty tree when creating zipper, None focus node, setting value on None focus, moving left/right from None or when no child exists, setting children on None focus, moving up from root, converting None tree to tree representation |