# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def closestKValues(self, root: TreeNode, target: float, k: int) -> List[int]:
        def dfs(root):
            if root is None:
                return
            dfs(root.left)
            if len(q) < k:
                q.append(root.val)
            else:
                if abs(root.val - target) >= abs(q[0] - target):
                    return
                q.popleft()
                q.append(root.val)
            dfs(root.right)

        q = deque()
        dfs(root)
        return list(q)
