2025-07-30 13:27:11 +0000 UTC

# 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 findTilt(self, root: Optional[TreeNode]) -> int:
        def dfs(node: Optional[TreeNode]) -> tuple[int, int]:
            if node is None:
                return 0, 0
            left_sum, left_tilt = dfs(node.left)
            right_sum, right_tilt = dfs(node.right)
            tilt_sum = left_tilt + right_tilt + abs(left_sum - right_sum)
            node_sum = node.val + left_sum + right_sum
            return node_sum, tilt_sum
        _, tilt_sum = dfs(root)
        return tilt_sum