refactor:RotateSinglyLinkedLists

Author: Swastik-Swarup-Dash

src/main/java/com/thealgorithms/datastructures/lists/RotateSinglyLinkedLists.java

@@ -1,33 +1,52 @@
 package com.thealgorithms.datastructures.lists;
 
 /**
- * Rotate a list
- * @author Bama Charan Chhandogi (https://github.com/BamaCharanChhandogi)
+ * Rotate a singly linked list
+ * 
  */
 
 public class RotateSinglyLinkedLists {
+
     public Node rotateRight(Node head, int k) {
         if (head == null || head.next == null || k == 0) {
             return head;
         }
 
-        Node curr = head;
-        int len = 1;
-        while (curr.next != null) {
-            curr = curr.next;
-            len++;
+        int length = getLength(head);
+        k = k % length;
+        if (k == 0) {
+            return head;
         }
 
-        curr.next = head;
-        k = k % len;
-        k = len - k;
-        while (k > 0) {
-            curr = curr.next;
-            k--;
-        }
+        Node last = getLastNode(head);
+        last.next = head;
 
-        head = curr.next;
-        curr.next = null;
+        int stepsToNewHead = length - k;
+        Node newLast = head;
+        while (stepsToNewHead > 1) {
+            newLast = newLast.next;
+            stepsToNewHead--;
+        }
+        head = newLast.next;
+        newLast.next = null;
         return head;
     }
+
+    private int getLength(Node head) {
+        int length = 0;
+        Node current = head;
+        while (current != null) {
+            length++;
+            current = current.next;
+        }
+        return length;
+    }
+
+    private Node getLastNode(Node head) {
+        Node last = head;
+        while (last.next != null) {
+            last = last.next;
+        }
+        return last;
+    }
 }