337. House Robber III

337. House Robber III

這一題是 198. House Robber213. House Robber II 的延伸題組,題目的情境相同,但是做法完全不同,是一題後序遍歷的問題。

# 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 rob(self, root: Optional[TreeNode]) -> int:

        def helper(node):
            if not node:
                return (0, 0)
            left = helper(node.left)
            right = helper(node.right)

            rob = node.val + left[1] + right[1]
            not_rob = max(left) + max(right)

            return rob, not_rob

        return max(helper(root))