Create rotate_linked_list.java

rotate_linked_list.java

@@ -0,0 +1,39 @@
+package linkedlists;
+
+public class RotateLinkedList {
+
+      public class ListNode {
+          int val;
+          ListNode next;
+          ListNode() {}
+          ListNode(int val) { this.val = val; }
+          ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+        }
+
+
+    public static ListNode rotateRight(ListNode head, int k) {
+
+            if(k ==0) return head;
+            int size = 1;
+
+            ListNode fast = head;
+            ListNode slow = head;
+
+            while(fast.next != null){
+                size++;
+                fast = fast.next;
+            }
+            //slow points to the item where the cycle starts
+            // use to break cycle later on
+            for(int cycle = size - k % size;  cycle > 1; cycle--){
+                slow = slow.next;
+            }
+
+            fast.next = head;
+            head = slow.next;
+            slow.next = null;
+
+            return head;
+
+        }
+    }