2026-01-07 11:11:18 +0300 MSK

# 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 maxProduct(self, root: Optional[TreeNode]) -> int:
        if root is None:
            return 0
        sums = {}
        def dfs_sum(node: Optional[TreeNode]) -> int:
            if node is None:
                return 0
            node_id = id(node)
            if node_id in sums:
                return sums[node_id]
            res = node.val + dfs_sum(node.left) + dfs_sum(node.right)
            sums[node_id] = res
            return res
        dfs_sum(root)
        root_sum = sums[id(root)]
        def dfs(node: Optional[TreeNode]) -> int:
            if node is None:
                return 0
            tree1 = sums[id(node)]
            tree2 = root_sum - tree1 
            res = max(tree1 * tree2, dfs(node.left), dfs(node.right))
            return res
        return max(dfs(root.left), dfs(root.right)) % (10 ** 9 + 7)