The singly linked list is used as the bottom layer to realize the data structure of the stack
Implementation of the stack:
package SingleLinkedListStack;
import ArrayStack.Stack;
import SingleLinkedList.Node;
import SingleLinkedList.SingleLinkedList;
/*
* 用链表作为栈的底层
*/
public class SingleLinkedListStack <E> implements Stack<E>{
// 用链表作为栈的底层
public SingleLinkedList<E> list;
public SingleLinkedListStack() {
list = new SingleLinkedList();
}
@Override
public void push(E e) {
// TODO Auto-generated method stub
list.addFirst(e);
}
@Override
public E pop() {
// TODO Auto-generated method stub
return (E) list.removeFirst();
}
@Override
public E peek() {
// TODO Auto-generated method stub
return list.getfirst();
}
@Override
public int getSize() {
// TODO Auto-generated method stub
return list.getSize();
}
@Override
public boolean isEmpty() {
// TODO Auto-generated method stub
return list.isEmpty();
}
@Override
public String toString() {
StringBuilder sb=new StringBuilder(); sb.append("stack ");
sb.append("push:>");
for(int i=0;i<list.getSize();i++) {
sb.append(list.get(i));
sb.append("->");
}
sb.append("null");
return sb.toString();
}
}
Stack test:
package SingleLinkedListStack;
public class SingleLinkedListStackTest {
public static void main(String[] args) {
SingleLinkedListStack st =new SingleLinkedListStack<Integer>();
for(int i=1;i<6;i++) {
st.push(i);
}
System.out.println(st);
for(int i=0;i<3;i++) {
st.pop();
}
System.out.println(st);
System.out.println(st.peek());
System.out.println(st.getSize());
System.out.println(st.isEmpty());
}
}
Test result:
Comparison of the time complexity of using an array to implement a stack and using a linked list to implement a stack:
Implementing a stack using an array: Implementing a stack
using a linked list
The additional implementation linked list code is as follows:
package SingleLinkedList;
/*
* 单链表的实现
*/
public class SingleLinkedList<E> {
private Node nullhead; //声明空头节点
private int size; // 链表存放的元素
public SingleLinkedList() {
nullhead =new Node(null,null);
size=0;
}
// 在链表头位置添加元素
public void addFirst(E e){
add(0,e);
}
public void addLast(E e) {
add(size,e);
}
//在任意位置添加元素
public void add(int index, E e) {
// TODO Auto-generated method stub
if(index<0||index>size) {
throw new IllegalArgumentException("add failed,index is invaild");
}
Node prev =nullhead;
for(int i=0;i<index;i++) {
prev =prev.next;
}
// 创建一个待插入的节点node
Node node =new Node(e);
// 将该节点挂接到链表中(要注意顺序，先连尾部先)
// node.next=prev.next;
// prev.next=node;
prev.next =new Node(e,prev.next); //等同于上面两行代码，比较简洁
// 维护size
size++;
}
// 删除元素首个
public Object removeFirst() {
return remove(0);
}
public E removerLast() {
return remove(size-1);
}
public E remove(int index) {
// TODO Auto-generated method stub
if(index<0||index>=size) {
throw new IllegalArgumentException("remove failed,index is invaild");
}
Node prev =nullhead; //
// 通过这个for循环，找到待删除的节点的前一个节点
for(int i=0;i<index;i++) {
prev=prev.next;
}
Node delnode =prev.next;//待删除的节点
prev.next =delnode.next; //开始连接
delnode.next=null; //断开连接
size--;
return (E) delnode.e;
}
public void set(int index,E e) {
if(index<0||index>=size) {
throw new IllegalArgumentException("set failed ,index is invaild");
}
// 先拿到头节点，以便遍历
Node cur =nullhead.next;
int i=0;
while(cur!=null) {
if(i==index) {
cur.e=e;
}
i++;
cur= cur.next;
}
}
public E get(int index) {
if(index<0||index>=size) {
throw new IllegalArgumentException("get failed ,index is invaild");
}
Node cur =nullhead.next;
int i=0;
while(cur!=null) {
if(i==index) {
return (E) cur.e;
}
i++;
cur=cur.next;
}
return null;
}
public E getfirst() {
return get(0);
}
public boolean isEmpty() {
return size==0;
}
public int getSize() {
return size;
}
//重写打印输出
public String toString() {
StringBuilder res=new StringBuilder();
res.append("linkedList:");
Node cur =nullhead.next;//第一个节点，也就是头节点
while(cur!=null) {
res.append(cur+"->");
cur=cur.next;
}
res.append("null");
return res.toString();
}
}
package SingleLinkedList;
/*
* 但链表表节点的封装
* 一个Node节点包含的数据是元素和下一个节点的连接
*/
public class Node <E>{
public E e;
public Node next;
public Node(E e, Node next) {
this.e = e;
this.next = next;
}
public Node(E e) {
this(e, null);
}
public Node() {
this(null, null);
}
@Override
public String toString() {
return e.toString();
}
}