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 1Maximum 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.
This is a very interesting question!
/**
* 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) {
if(!root) return 0;
if(!root->left && !root->right) return root->val;
int rIn = root->val, rOut = 0;
if(root->left) {
rIn += rob(root->left->left) + rob(root->left->right);
rOut = rob(root->left);
}
if(root->right) {
rIn += rob(root->right->left) + rob(root->right->right);
rOut += rob(root->right);
}
return rIn > rOut ? rIn : rOut;
}
};