1339. Maximum Product of Splitted Binary Tree.py

# 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: TreeNode) -> int:
        
        """
        total = 0
        def get_sum(node):
            nonlocal total
            if not node:
                return
            
            total += node.val
            get_sum(node.left)
            get_sum(node.right)
        
        get_sum(root)
        
        def postorder(node):
            if not node:
                return 0
            
            left = postorder(node.left)
            right = postorder(node.right)
            
            return node.val + left + right
        
        def dfs(node):
            nonlocal res
            if not node:
                return
            
            if not node.left and not node.right:
                res = max(res, node.val * (total-node.val))
                return
            
            sub = postorder(node)
            res = max(res, sub * (total-sub))
            dfs(node.left)
            dfs(node.right)
        
        res = 0
        
        dfs(root)
        
        return res % (10**9+7)
        """
        dic = collections.defaultdict(int)
        def get_sum(node):
            nonlocal dic
            if not node:
                return 0
            
            left = get_sum(node.left)
            right = get_sum(node.right)
            
            dic[node] = node.val + left + right
            
            return node.val + left + right
        
        get_sum(root)
        total = dic[root]
        res = 0
        
        def dfs(node):
            nonlocal res
            if not node:
                return
            
            res = max(res, dic[node] * (total-dic[node]))
            dfs(node.left)
            dfs(node.right)
        
        dfs(root.left)
        dfs(root.right)
        
        return res % (10**9+7)