/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
int rob(TreeNode* root) {
dfs(root);
return max(pk[root], unpk[root]);
}
private:
unordered_map<TreeNode*, int> pk, unpk;
void dfs(TreeNode* root) {
if (root) {
dfs(root->left);
dfs(root->right);
pk[root] = unpk[root->left] + unpk[root->right] + root->val;
unpk[root] = max(pk[root->left], unpk[root->left]) + max(pk[root->right], unpk[root->right]);
}
return;
}
};