leetcode337 -- House Robber III

# 小郑之家~

### 题目

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:

Input: [3,2,3,null,3,null,1]

3
/ \
2   3
\   \
3   1

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

Example 2:

Input: [3,4,5,1,3,null,1]

3
/ \
4   5
/ \   \
1   3   1

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



class TreeNode(object):
def __init__(self, x):
self.val = x
self.left = None
self.right = None

class Solution(object):
def rob(self, root):
return max(self.dfs(root))

def dfs(self,node):
if not node:
return 0,0
l, r = self.dfs(node.left), self.dfs(node.right)
return max(l)+max(r), node.val+l[0]+r[0]