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.
// 12ms, 93%
/**
* 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 {
// return pair amount with & without robbing root
pair<int,int> check(TreeNode* root) {
if (!root) return {0, 0};
auto l = check(root->left);
auto r = check(root->right);
return { root->val + l.second + r.second,
max(l.first,l.second) + max(r.first,r.second)};
}
public:
int rob(TreeNode* root) {
auto r = check(root);
return max(r.first, r.second);
}
};