337. 打家劫舍 III

 1 /**
 2  * Definition for a binary tree node.
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution 
11 {
12     unordered_map<TreeNode *, int> sums;//记忆化搜索
13 public:
14     int rob(TreeNode* root) 
15     {
16         return tryRob(root);
17     }
18     
19     int tryRob(TreeNode* node) 
20     {
21         if (!node) return 0;
22         if (sums.count(node)) return sums[node];
23 
24         //偷取该节点
25         int res1 = 0;
26         if(node->left) res1 += (tryRob(node->left->left) + tryRob(node->left->right));
27         if(node->right) res1 += (tryRob(node->right->left) + tryRob(node->right->right));
28         res1 += node->val;
29         
30         //不偷取该节点
31         int res2 = tryRob(node->left) + tryRob(node->right);
32         sums[node] = max(res1, res2);
33         return sums[node];
34     }
35 };