update 109

Author: fishercoder1534

src/main/java/com/fishercoder/solutions/firstthousand/_109.java

@@ -15,7 +15,8 @@ public TreeNode toBstRecursively(ListNode start, ListNode end) {
             } else {
                 ListNode slow = start;
                 ListNode fast = start;
-                while (fast != end && fast.next != end) {//here is the key: we check if fast != end, not fast != null
+                //here is the key: we check if fast != end, not fast != null
+                while (fast != end && fast.next != end) {
                     slow = slow.next;
                     fast = fast.next.next;
                 }