Leetcode no. 337

337. House Robber III

 

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   1

Maximum 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.

/** * Definition for a binary tree node. * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {    public int rob(TreeNode root){        int[] res= robRec(root);        return Math.max(res[0], res[1]);    }    private int[] robRec(TreeNode n){        if (n==null) return new int[2];        int[] left= robRec(n.left);        int[] right= robRec(n.right);        int[] res= new int[2];        res[0]= n.val+left[1]+right[1];        res[1]= Math.max(left[0],left[1])+Math.max(right[0],right[1]);        return res;    }}