LoopInLinkedList: make comparison with null earlier

Author: andrei-punko

src/main/java/by/andd3dfx/collections/LoopInLinkedList.java

@@ -27,21 +27,21 @@ public static boolean isPresent(Node head) {
 
         while (true) {
             fast = fast.next;
-            if (fast == slow) {
-                return true;
-            }
             if (fast == null) {
                 return false;
             }
-
-            slow = slow.next;
-            fast = fast.next;
             if (fast == slow) {
                 return true;
             }
+
+            slow = slow.next;
+            fast = fast.next;
             if (fast == null) {
                 return false;
             }
+            if (fast == slow) {
+                return true;
+            }
         }
     }
 }