Update 0213.打家劫舍II.md

problems/0213.打家劫舍II.md

@@ -98,7 +98,28 @@ public:
 
 
 Java：
+```Java
+class Solution {
+    public int rob(int[] nums) {
+        if (nums == null || nums.length == 0)
+            return 0;
+        int len = nums.length;
+        if (len == 1)
+            return nums[0];
+        return Math.max(robAction(nums, 0, len - 1), robAction(nums, 1, len));
+    }
 
+    int robAction(int[] nums, int start, int end) {
+        int x = 0, y = 0, z = 0;
+        for (int i = start; i < end; i++) {
+            y = z;
+            z = Math.max(y, x + nums[i]);
+            x = y;
+        }
+        return z;
+    }
+}
+```
 
 Python：