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栈的实现
// 栈的基本方法
public interface Stack<E> {
void push(E e);
E pop();
E peek();
int getSize();
boolean isEmpty();
}
// 链表的基本方法的实现
public class LinkedList<E> {
private Node dummyHead;
private int size;
private class Node {
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();
}
}
public LinkedList() {
dummyHead = new Node(null, null);
size = 0;
}
public int getSize() {
return size;
}
public boolean isEmpty() {
return size == 0;
}
/**
* 添加
* 不是一个常用的操作
* @param index
* @param e
*/
public void add(int index, E e) {
if(index < 0 || index > size)
throw new IllegalArgumentException("Add failed, Illegal index.");
Node prev = dummyHead;
for(int i = 0; i < index; i++) prev = prev.next;
prev.next = new Node(e, prev.next);
size++;
}
/**
* 在链表头部添加数据
* @param e
*/
public void addFirst(E e) {
add(0, e);
}
/**
* 在链表末尾添加元素
* @param e
*/
public void addList(E e) {
add(size, e);
}
/**
* 获取索引对应的值
* @param index
* @return
*/
public E get(int index) {
if(index < 0 || index > size)
throw new IllegalArgumentException("Add failed, Illegal index.");
Node cur = dummyHead.next;
for(int i = 0; i < index; i++) cur = cur.next;
return cur.e;
}
/**
* 获取第一个元素
* @return
*/
public E getFirst() {
return get(0);
}
/**
* 获取最后一个元素
* @return
*/
public E getLast() {
return get(size-1);
}
/**
* 修改第index位置的元素
* @param index
* @param e
*/
public void set(int index, E e) {
if(index < 0 || index > size)
throw new IllegalArgumentException("Add failed, Illegal index.");
Node cur = dummyHead.next;
for(int i = 0; i < index; i++) cur = cur.next;
cur.e = e;
}
/**
* 遍历链表中的元素
* @param e
* @return
*/
public boolean contains(E e) {
Node cur = dummyHead.next;
while(cur != null) {
if(cur.e.equals(e))
return true;
cur = cur.next;
}
return false;
}
/**
* 删除指定位置的元素
* @param index
* @return
*/
public E remove(int index) {
if(index < 0 || index > size)
throw new IllegalArgumentException("Add failed, Illegal index.");
Node prev = dummyHead;
for(int i = 0; i < index; i++) prev = prev.next;
Node retNode = prev.next;
prev.next = retNode.next;
retNode.next = null;
size--;
return retNode.e;
}
/**
* 删除第一个元素
* @return
*/
public E removeFirst() {
return remove(0);
}
/**
* 删除最后一个
* @return
*/
public E removeLast() {
return remove(size - 1);
}
/**
* 遍历链表
* @return
*/
@Override
public String toString() {
StringBuilder res = new StringBuilder();
Node cur = dummyHead.next;
while(cur != null) {
res.append(cur + "-->");
cur = cur.next;
}
res.append("NULL");
return res.toString();
}
}
// 借助链表实现栈操作
public class LinkedListStack<E> implements Stack<E> {
private LinkedList<E> list;
public LinkedListStack() {
list = new LinkedList<>();
}
/**
* 入栈
* @param e
*/
@Override
public void push(E e) {
list.addFirst(e);
}
/**
* 出栈
* @return
*/
@Override
public E pop() {
return list.removeFirst();
}
/**
* 获取栈顶元素
* @return
*/
@Override
public E peek() {
return list.getFirst();
}
/**
* 获取栈数量
* @return
*/
@Override
public int getSize() {
return list.getSize();
}
/**
* 判断栈为空
* @return
*/
@Override
public boolean isEmpty() {
return list.isEmpty();
}
/**
* 遍历栈元素
* @return
*/
@Override
public String toString() {
StringBuilder res = new StringBuilder();
res.append("Stack top ");
res.append(list);
return res.toString();
}
public static void main(String[] args) {
LinkedListStack<Integer> stack = new LinkedListStack<>();
for(int i = 0; i < 5; i++) {
stack.push(i);
System.out.println(stack);
}
stack.pop();
System.out.println(stack);
}
}
队列的实现
// 队列基本操作
public interface Queue<E> {
int getSize();
boolean isEmpty();
void enqueue(E e);
E dequeue();
E getFront();
}
// 队列的基本操作
public class LinkedListQueue<E> implements Queue<E> {
// 定义的节点
private class Node {
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();
}
}
// 定义一个头指针和尾指针
private Node head, tail;
private int size;
public LinkedListQueue() {
this.head = null;
this.tail = null;
this.size = 0;
}
/**
* 获取队列元素的数量
* @return
*/
@Override
public int getSize() {
return size;
}
/**
* 判断队列是否为空
* @return
*/
@Override
public boolean isEmpty() {
return size == 0;
}
/**
* 入队操作
* @param e
*/
@Override
public void enqueue(E e) {
if(tail == null) {
tail = new Node(e);
head = tail;
}else{
tail.next = new Node(e);
tail = tail.next;
}
size++;
}
/**
* 出队元素
* @return
*/
@Override
public E dequeue() {
if(isEmpty())
throw new IllegalArgumentException("不能出队!");
Node retNode = head;
head = head.next;
retNode.next = null;
if(head == null)
tail = null;
size--;
return retNode.e;
}
/**
* 获取队首
* @return
*/
@Override
public E getFront() {
if(isEmpty())
throw new IllegalArgumentException("不能出队!");
return head.e;
}
@Override
public String toString() {
StringBuilder res = new StringBuilder();
res.append("Queue front ");
Node cur = head;
while(cur != null){
res.append(cur + "-->");
cur = cur.next;
}
res.append("NULL tail");
return res.toString();
}
public static void main(String[] args) {
LinkedListQueue<Integer> queue = new LinkedListQueue<>();
for(int i = 0; i < 10; i++) {
queue.enqueue(i);
System.out.println(queue);
if(i % 3 == 2) {
queue.dequeue();
System.out.println(queue);
}
}
}
}