Re: [閒聊] 每日leetcode

[dont (dont)]

2641. Cousins in Binary Tree II

## 思路

BFS
每一層都用Hashtable記錄同父節點的和
然後再更新值 (= 整層總和 - 同父節點的和)

## Code

```python
class Solution:
    def replaceValueInTree(self, root: Optional[TreeNode]) ->
Optional[TreeNode]:

        root.val = 0
        queue = deque()
        if root.left:
            queue.append((root, root.left))
        if root.right:
            queue.append((root, root.right))

        while queue:
            total = 0
            table = defaultdict(int)
            for _ in range(len(queue)):
                parent, node = queue.popleft()
                total += node.val
                table[parent] += node.val
                if node.left:
                    queue.append((node, node.left))
                if node.right:
                    queue.append((node, node.right))

            for parent in table:
                if parent.left:
                    parent.left.val = total - table[parent]
                if parent.right:
                    parent.right.val = total - table[parent]

        return root
```

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