solves house robber ii

Author: anishLearnsToCode

README.md

@@ -172,7 +172,7 @@
 | 209  | [Minimum Size Subarray Sum](https://leetcode.com/problems/minimum-size-subarray-sum)                                                                      |                                                             [![Java](assets/java.png)](src/MinimumSizeSubarraySum.java)                                                              |                                                                                                                                   |
 | 210  | [Course Schedule II](https://leetcode.com/problems/course-schedule-ii)                                                                                    |                                                                [![Java](assets/java.png)](src/CourseScheduleII.java)                                                                 |                                                                                                                                   |
 | 211  | [Design Add and Search Words Data Structure](https://leetcode.com/problems/design-add-and-search-words-data-structure)                                    |                                                      [![Java](assets/java.png)](src/DesignAddAndSearchWordsDataStructure.java)                                                       |                                                                                                                                   |
-| 213  | [House Robber II](https://leetcode.com/problems/house-robber-ii)                                                                                          |                                                                                                                                                                                      |                                                                                                                                   |
+| 213  | [House Robber II](https://leetcode.com/problems/house-robber-ii)                                                                                          |                                                                  [![Java](assets/java.png)](src/HouseRobberII.java)                                                                  |                                                                                                                                   |
 | 215  | [Kth Largest Element in an Array](https://leetcode.com/problems/kth-largest-element-in-an-array)                                                          |                                                           [![Java](assets/java.png)](src/KthLargestElementInAnArray.java)                                                            |                                                                                                                                   |
 | 216  | [Combination Sum III](https://leetcode.com/problems/combination-sum-iii)                                                                                  |                                                                                                                                                                                      |                                                                                                                                   |
 | 217  | [Contains Duplicate](https://leetcode.com/problems/contains-duplicate)                                                                                    |                                 [![Java](assets/java.png)](src/ContainsDuplicate.java) [![Python](assets/python.png)](python/contains_duplicate.py)                                  |                                                                                                                                   |

src/HouseRobberII.java

@@ -0,0 +1,25 @@
+// https://leetcode.com/problems/house-robber-ii
+// T: O(N)
+// S: O(1)
+
+public class HouseRobberII {
+    public int rob(int[] array) {
+        if (array.length == 1) return array[0];
+        if (array.length == 2) return Math.max(array[0], array[1]);
+
+        return Math.max(
+                rob(array, 0, array.length - 2),
+                rob(array, 1, array.length - 1)
+        );
+    }
+
+    public int rob(int[] array, int start, int end) {
+        int a = array[start], b = Math.max(array[start], array[start + 1]), c = Math.max(a, b);
+        for (int i = start + 2 ; i <= end ; i++) {
+            c = Math.max(array[i] + a, b);
+            a = b;
+            b = c;
+        }
+        return c;
+    }
+}