Given a sorted singly linked list without a tail $($e$.$g$,$ head $(1)->(2)->(3)->(4)),$ return the interquartile range of the data set using the slow and fast pointer approach OR using a methodology that does not iterate over the linked list twice. You must not iterate over the entire linked list more than once and you cannot use arrays, vectors, lists or an STL implementation of List ADT in this problem. You must not more than one loop for this problem. If you prohibit the above requirements, you will incur a $20\%$ penalty on your score.