单个链表中头尾插入的区别

Question

I'm trying to understand the difference between a tail insert (code below) and a head insert. Is it the order in which we assign the next node?

Given: 13, 15, 18, 20.

Tail insert: 13 -> 15 -> 18 -> 20

Head insert: 20 -> 18 -> 15 -> 13?

public class MylinkedList
{
  // Initialize head node
  private MyNode head;

  // Node creation
  public void tailInsert(int data)
  {
    if(head == null)
    {
      head = new MyNode(data);
      return;
    }

    // While .next of head != null then we set the lastNode to the .next
    MyNode lastNode = head;
    // Find the last node in the list and set it to lastNode
    while(lastNode.next != null)
    {
      lastNode = lastNode.next;
    }

    lastNode.next = new MyNode(data);
  }

public class MyNode
{
  public int data;
  public MyNode next;

  MyNode(data)
  {
    this.data = data
    this.next = null;
  }
}

Answer 1

The difference is in the names.

A "tail insert" inserts the new object at the tail of the list and thus the list has the same order as the order in which elements are added.

A "head insert" inserts the new object at the head of the list, so the list has the reverse order compared to the order in which elements are added.

"Head" is a synonym for "front end" of the list; "tail" is a synonym for the "back end" of the list. Think about a line of people waiting for a bus; this is generally a case of tail insertion, at least where people are polite. The head of the line arrived first and gets on the bus first.