private void validateInput(ListNode listNode, int k) {
    if (listNode == null) {
      throw new IllegalArgumentException("You can't pass a null ListNode as argument.");
    }
    if (k < 0) {
      throw new IllegalArgumentException("You can't pass a negative position.");
    }
  }
Iterative algorithm to resolve this problem based on two pointers to avoid the usage of an
auxiliary data structure. The complexity order of this algorithm is O(N) as in the previous
implementations, but in space terms, the complexity order is equals to O(1).
src/main/java/com/github/pedrovgs/problem58/FindKthElement.java