Re: [閒聊] 每日leetcode

[Rushia (早瀬ユウカの体操服 )]

https://leetcode.com/problems/add-one-row-to-tree
623. Add One Row to Tree
給你一個二元樹，請在深度為depth的位置插入一列值為val的節點。

思路：
1.用 bfs 算深度找到 depth - 1 的位置，直接插入。
2.depth == 1 是 corner case 要額外處理。

py code:
---------------------------------------------------------
class Solution:
    def addOneRow(self, root: Optional[TreeNode], val: int, depth: int) ->
Optional[TreeNode]:
        if depth == 1:
            return TreeNode(val, root, None)

        q = deque()
        q.append(root)
        h = 1
        while q:
            size = len(q)
            for i in range(size):
                x = q.popleft()
                if h == depth - 1:
                    x.left = TreeNode(val, x.left, None)
                    x.right = TreeNode(val, None, x.right)
                    continue
                if x.left:
                    q.append(x.left)
                if x.right:
                    q.append(x.right)
            h += 1
        return root
---------------------------------------------------------

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