human
Can you provide a Python code to determine the maximum amount of money the thief can rob tonight without alerting the police given the following:
Solve in Python:
The thief has found himself a new place for his thievery again. There is only one entrance to this area, called the "root." Besides the root, each house has one and only one parent house. After a tour, the smart thief realized that "all houses in this place forms a binary tree". It will automatically contact the police if two directly-linked houses were broken into on the same night.


Determine the maximum amount of money the thief can rob tonight without alerting the police.

Example 1:

     3
    / \
   2   3
    \   \ 
     3   1

Maximum amount of money the thief can rob = 3 + 3 + 1 = 7.

Example 2:

     3
    / \
   4   5
  / \   \ 
 1   3   1

Maximum amount of money the thief can rob = 4 + 5 = 9.

Credits:Special thanks to @dietpepsi for adding this problem and creating all test cases.
assistant
#Here is Python code to determine the maximum amount of money the thief can rob tonight without alerting the police.

# Definition for a binary tree node.
 # class TreeNode:
 #     def __init__(self, x):
 #         self.val = x
 #         self.left = None
 #         self.right = None
 
 class Solution:
     def rob(self, root):
         self.dict = {}
         return self.recurse(root)
         
     def recurse(self, root):
         if root is None:
             return 0
         if root in self.dict:
             return self.dict[root]
         else:
             x = self.recurse(root.left)
             y = self.recurse(root.right)
             a = 0 if root.left is None else self.recurse(root.left.left)
             b = 0 if root.left is None else self.recurse(root.left.right)
             c = 0 if root.right is None else self.recurse(root.right.left)
             d = 0 if root.right is None else self.recurse(root.right.right)
             ans = max(root.val+a+b+c+d , x+y)
             self.dict[root] = ans
             return ans