| 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 | # Edge Case: Handle None tree by initializing with empty path |
| 4 | self.tree = tree if tree is not None else {"value": None, "left": None, "right": None} |
| 5 | self.path = path |
| 6 | |
| 3 | 7 | @staticmethod |
| 4 | 8 | def from_tree(tree: dict) -> "Zipper": |
| 5 | | pass |
| 9 | # Edge Case: Handle None input tree |
| 10 | if tree is None: |
| 11 | return Zipper(None) |
| 12 | return Zipper(tree) |
| 6 | 13 | |
| 7 | 14 | def value(self) -> int: |
| 8 | | pass |
| 15 | # Edge Case: Handle None tree |
| 16 | if self.tree is None: |
| 17 | return None |
| 18 | return self.tree["value"] |
| 9 | 19 | |
| 10 | 20 | def set_value(self, value: int) -> "Zipper": |
| 11 | | pass |
| 21 | # Edge Case: Handle None tree |
| 22 | if self.tree is None: |
| 23 | new_tree = {"value": value, "left": None, "right": None} |
| 24 | else: |
| 25 | new_tree = {"value": value, "left": self.tree["left"], "right": self.tree["right"]} |
| 26 | |
| 27 | # Reconstruct tree with new value |
| 28 | new_zipper = Zipper(new_tree, self.path[:]) |
| 29 | current = new_zipper |
| 30 | for step in reversed(new_zipper.path): |
| 31 | parent_tree = step["tree"].copy() |
| 32 | if step["direction"] == "left": |
| 33 | parent_tree["left"] = current.tree |
| 34 | else: # right |
| 35 | parent_tree["right"] = current.tree |
| 36 | current = Zipper(parent_tree, step["path"][:]) |
| 37 | |
| 38 | # Navigate back to the original focus position |
| 39 | result = current |
| 40 | for step in self.path: |
| 41 | if step["direction"] == "left": |
| 42 | result = result.left() |
| 43 | else: # right |
| 44 | result = result.right() |
| 45 | return result |
| 12 | 46 | |
| 13 | 47 | def left(self) -> "Zipper | None": |
| 14 | | pass |
| 48 | # Edge Case: Handle None tree or None left child |
| 49 | if self.tree is None or self.tree["left"] is None: |
| 50 | return None |
| 51 | new_path = self.path + [{"tree": self.tree, "direction": "left", "path": self.path[:]}] |
| 52 | return Zipper(self.tree["left"], new_path) |
| 15 | 53 | |
| 16 | 54 | def set_left(self, tree: dict | None) -> "Zipper": |
| 17 | | pass |
| 55 | # Edge Case: Handle None tree |
| 56 | if self.tree is None: |
| 57 | new_tree = {"value": None, "left": tree, "right": None} |
| 58 | else: |
| 59 | new_tree = {"value": self.tree["value"], "left": tree, "right": self.tree["right"]} |
| 60 | |
| 61 | # Reconstruct tree with new left subtree |
| 62 | new_zipper = Zipper(new_tree, self.path[:]) |
| 63 | current = new_zipper |
| 64 | for step in reversed(new_zipper.path): |
| 65 | parent_tree = step["tree"].copy() |
| 66 | if step["direction"] == "left": |
| 67 | parent_tree["left"] = current.tree |
| 68 | else: # right |
| 69 | parent_tree["right"] = current.tree |
| 70 | current = Zipper(parent_tree, step["path"][:]) |
| 71 | |
| 72 | # Navigate back to the original focus position |
| 73 | result = current |
| 74 | for step in self.path: |
| 75 | if step["direction"] == "left": |
| 76 | result = result.left() |
| 77 | else: # right |
| 78 | result = result.right() |
| 79 | return result |
| 18 | 80 | |
| 19 | 81 | def right(self) -> "Zipper | None": |
| 20 | | pass |
| 82 | # Edge Case: Handle None tree or None right child |
| 83 | if self.tree is None or self.tree["right"] is None: |
| 84 | return None |
| 85 | new_path = self.path + [{"tree": self.tree, "direction": "right", "path": self.path[:]}] |
| 86 | return Zipper(self.tree["right"], new_path) |
| 21 | 87 | |
| 22 | 88 | def set_right(self, tree: dict | None) -> "Zipper": |
| 23 | | pass |
| 89 | # Edge Case: Handle None tree |
| 90 | if self.tree is None: |
| 91 | new_tree = {"value": None, "left": None, "right": tree} |
| 92 | else: |
| 93 | new_tree = {"value": self.tree["value"], "left": self.tree["left"], "right": tree} |
| 94 | |
| 95 | # Reconstruct tree with new right subtree |
| 96 | new_zipper = Zipper(new_tree, self.path[:]) |
| 97 | current = new_zipper |
| 98 | for step in reversed(new_zipper.path): |
| 99 | parent_tree = step["tree"].copy() |
| 100 | if step["direction"] == "left": |
| 101 | parent_tree["left"] = current.tree |
| 102 | else: # right |
| 103 | parent_tree["right"] = current.tree |
| 104 | current = Zipper(parent_tree, step["path"][:]) |
| 105 | |
| 106 | # Navigate back to the original focus position |
| 107 | result = current |
| 108 | for step in self.path: |
| 109 | if step["direction"] == "left": |
| 110 | result = result.left() |
| 111 | else: # right |
| 112 | result = result.right() |
| 113 | return result |
| 24 | 114 | |
| 25 | 115 | def up(self) -> "Zipper | None": |
| 26 | | pass |
| 116 | # Edge Case: Handle when already at root (no path) |
| 117 | if not self.path: |
| 118 | return None |
| 119 | last_step = self.path[-1] |
| 120 | return Zipper(last_step["tree"], last_step["path"][:]) |
| 27 | 121 | |
| 28 | 122 | def to_tree(self) -> dict: |
| 29 | | pass |
| 123 | # Navigate to root and return the tree |
| 124 | current = self |
| 125 | path_length = len(current.path) |
| 126 | # Add a safety check to prevent potential infinite loop |
| 127 | max_iterations = 1000 |
| 128 | iterations = 0 |
| 129 | |
| 130 | while current.path and iterations < max_iterations: |
| 131 | current = current.up() |
| 132 | iterations += 1 |
| 133 | |
| 134 | if iterations >= max_iterations: |
| 135 | raise RuntimeError("Maximum iterations exceeded while navigating to root") |
| 136 | |
| 137 | return current.tree |
| 138 | |
| 139 | # Handled Edge Cases: None tree, None left/right child, setting value/left/right on None tree, navigating up from root |