LeetCode 337.

package lc_337;

public class Solution {
    public int rob(TreeNode root) {
        // Time Exceeded
        // return recur(root, 0, false);

        int[] ans = recursion(root);
        return Math.max(ans[0], ans[1]);
    }

    public int recur(TreeNode root, int value, boolean banned){
        if (root == null) return 0;
        if (banned) return value + recur(root.left, value, false) + recur(root.right, value, false);

        int take = root.val, not_take = 0;
        if (root.left != null){
            take += recur(root.left, value, true);
            not_take += recur(root.left, value, false);
        }
        if (root.right != null){
            take += recur(root.right, value, true);
            not_take += recur(root.right, value, false);
        }
        return Math.max(take, not_take);
    }

    public int[] recursion(TreeNode root){
        if (root == null) return new int[2];
        int[] r = recursion(root.right);
        int[] l = recursion(root.left);
        int[] v = new int[2];

        v[0] = root.val + r[1] + l[1]; // take account of current root
        v[1] = Math.max(r[0], r[1]) + Math.max(l[0], l[1]);  // not take account of current root
        return v;
    }
}