Add 213_House_Robber_II.java

Author: Sean Prashad

Dynamic Programming/213_House_Robber_II.java

@@ -0,0 +1,24 @@
+class Solution {
+    public int rob(int[] nums) {
+        if (nums == null || nums.length == 0) {
+            return 0;
+        }
+        if (nums.length == 1) {
+            return nums[0];
+        }
+
+        return Math.max(helper(nums, 0, nums.length - 2), helper(nums, 1, nums.length - 1));
+    }
+
+    private int helper(int[] nums, int start, int end) {
+        int currHouse = 0, twoHousesAgo = 0, oneHouseAgo = 0;
+
+        for (int i = start; i <= end; i++) {
+            currHouse = Math.max(twoHousesAgo + nums[i], oneHouseAgo);
+            twoHousesAgo = oneHouseAgo;
+            oneHouseAgo = currHouse;
+        }
+
+        return currHouse;
+    }
+}