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| 1 | +# Definition for a binary tree node. |
| 2 | +# class TreeNode: |
| 3 | +# def __init__(self, val=0, left=None, right=None): |
| 4 | +# self.val = val |
| 5 | +# self.left = left |
| 6 | +# self.right = right |
| 7 | +class Solution: |
| 8 | + def amountOfTime(self, root: Optional[TreeNode], start: int) -> int: |
| 9 | + def dfs(node): |
| 10 | + if node is None: |
| 11 | + return |
| 12 | + if node.left: |
| 13 | + graph[node.val].append(node.left.val) |
| 14 | + graph[node.left.val].append(node.val) |
| 15 | + if node.right: |
| 16 | + graph[node.val].append(node.right.val) |
| 17 | + graph[node.right.val].append(node.val) |
| 18 | + dfs(node.left) |
| 19 | + dfs(node.right) |
| 20 | + |
| 21 | + graph = defaultdict(list) |
| 22 | + dfs(root) |
| 23 | + visited = set() |
| 24 | + queue = deque([start]) |
| 25 | + time = -1 |
| 26 | + |
| 27 | + while queue: |
| 28 | + time += 1 |
| 29 | + for _ in range(len(queue)): |
| 30 | + current_node = queue.popleft() |
| 31 | + visited.add(current_node) |
| 32 | + for neighbor in graph[current_node]: |
| 33 | + if neighbor not in visited: |
| 34 | + queue.append(neighbor) |
| 35 | + |
| 36 | + return time |
| 37 | + |
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