Implement House Robber III for binary tree

Author: harshithasudhakar

Binary Tree/Problems/HouseRobberIII.java

@@ -0,0 +1,38 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode() {}
+ *     TreeNode(int val) { this.val = val; }
+ *     TreeNode(int val, TreeNode left, TreeNode right) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+class HouseRobberIII {
+    public int rob(TreeNode root) {
+        int[] result = postorder(root);
+        return Math.max(result[0], result[1]);
+    }
+
+    int[] postorder(TreeNode node){
+        if(node == null){
+            return new int[]{0,0};
+        }
+
+        int[] left = postorder(node.left);
+        int[] right = postorder(node.right);
+
+        int robLeft = left[0];
+        int skipLeft = left[1];
+
+        int robRight = right[0];
+        int skipRight = right[1];
+
+        return new int[]{node.val+skipLeft+skipRight, Math.max(robLeft, skipLeft)+Math.max(robRight, skipRight)};
+    }
+}