JavaAlgorithms/DataStructures/Lists/CountSinglyLinkedListRecursion.java

package DataStructures.Lists;

public class CountSinglyLinkedListRecursion extends SinglyLinkedList {
  public static void main(String[] args) {
    CountSinglyLinkedListRecursion list = new CountSinglyLinkedListRecursion();
    for (int i = 1; i <= 5; ++i) {
      list.insert(i);
    }
    assert list.count() == 5;
  }

  /**
   * Calculate the count of the list manually using recursion.
   *
   * @param head head of the list.
   * @return count of the list.
   */
  private int countRecursion(Node head) {
    return head == null ? 0 : 1 + countRecursion(head.next);
  }
  /** Returns the count of the list. */
  @Override
  public int count() {
    return countRecursion(getHead());
  }
}