详谈双向链表的实现与简单操作

标签：排序算法   线性表   双向链表   数据结构   算法   

  单链表的插入操作，除了首结点之外必须在某个结点的后面进行，而在双向链表中，在一个已知的结点之前或之后都可以。

1）s.prev = p.prev;

<strong>public class DoubleLink {
 public Link first;
 public Link last;
 public DoubleLink() { // 构造器初始化
  this.last = null;
  this.first = null;
 }
 public boolean isEmpty() { // 判断是否为空
  return first == null;
 }
 public void insertFirst(int data) { // 将元素插入链表头
  Link link = new Link(data);
  if (isEmpty())
   last = link; // 如果为空，last需要改变
  else
   first.prev = link;
  link.next = first;
  first = link;
 }
 public void insertLast(int data) { // 将元素插入链表尾
  Link link = new Link(data);
  if (isEmpty())
   last = link;
  else
   last.prev = link;
  link.prev = last;
  last = link;
 }
 public boolean insertAfter(int key, int idata) { // 在某元素后插入
  Link current = first;
  while (current.data != key) {
   current = current.next;
  }
  Link link = new Link(idata);
  if (current == last) {
   link.next = null;
   last = link;
  } else {
   link.next = current.next;
   current.next.prev = link;
  }
  link.prev = current;
  current.next = link;
  return true;
 }
 public Link deleteKey(int key) { // 删除某项元素
  Link current = first;
  while (current.data != key) {
   current = current.next;
  }
  first = current.next;
  if (current == last)
   last = current.prev;
  else
   current.next.prev = current.prev;
  return current;
 }
 public Link deleteFirst() { // 删除表开头的元素
  Link temp = first;
  if (first.next == null)
   last = null;
  else
   first.next.prev = null; // first结点的next字段引用的链结点的prev字段
  first = first.next;
  return temp;
 }
 public Link deleteLast() { // 删除表末尾的元素
  Link temp = last;
  if (first.next == null)
   first = null;
  else
   last.prev.next = null;
  last = last.prev;
  return temp;
 }
 public void showFirst() {// 前向展示
  Link current = last;
  while (current != null) {
   current.show();
   current = current.prev;
  }
 }
 public void showLast() {// 后向展示
  Link current = first;
  while (current != null) {
   current.show();
   current = current.next;
  }
 }
 public static void main(String[] args) {
  DoubleLink dlink = new DoubleLink();
  dlink.insertFirst(1);
  dlink.insertFirst(3);
  dlink.insertFirst(2);
  dlink.insertAfter(2, 4);
  dlink.showFirst();
 }
}
class Link {
 public int data; // 存放的数据
 public Link prev;// 对前一项的引用，直接前驱
 public Link next;// 对后一项的引用，直接后继
 public Link(int data) {
  this.data = data;
 }
 public void show() {
  System.out.println(data + " ");
 }
}</strong>

详谈双向链表的实现与简单操作

标签：排序算法   线性表   双向链表   数据结构   算法   

原文地址：http://blog.csdn.net/qq_21394609/article/details/44871175