java——链表、链表栈 LinkedListStack、链表队列 LinkedListQueue

LikedList：

package Date_pacage;

public class LinkedList<E> {
    public static void main(String[] args) {
        LinkedList<Integer> linkedList = new LinkedList<>();
        for(int i = 0 ; i < 5 ; i ++) {
            linkedList.addFirst(i);
            System.out.println(linkedList);
        }
        linkedList.add(2,  666);
        System.out.println(linkedList);
        linkedList.remove(2);
        System.out.println(linkedList);
    }
    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();
        }
    }
    private Node dummyHead;
    private int size;

    public LinkedList() {
        dummyHead = new Node(null, null);
        size = 0;
    }
    public int getSize() {
        return size;
    }
    public boolean isEmpty() {
        return size == 0;
    }
    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;
        }
//            Node node = new Node(e);
//            node.next = prev.next;
//            prev.next = node;
        prev.next = new Node(e, prev.next);
        size ++;
    }
    public void addFirst(E e) {
//        Node node = new Node(e);
//        node.next = head;
//        head = node;
        add(0, e);
    }
    public void addLast(E e) {
        add(size, e);
    }
    public E get(int index) {
        if(index < 0 || index > size) {
            throw new IllegalArgumentException("Get failed. Illegal index.");
        }
        Node cur = dummyHead.next;
        for(int i = 0 ; i < index ; i ++) {
            cur = cur.next;
        }
        return cur.e;
    }
    public E getFirst() {
        return get(0);
    }
    public E getLast() {
        return get(size - 1);
    }
    //修改链表的第index位置的元素为e
    public void set(int index, E e) {
        if(index < 0 || index > size) {
            throw new IllegalArgumentException("Get failed. Illegal index.");
        }
        Node cur = dummyHead.next;
        for(int i = 0; i < index ; i ++) {
            cur = cur.next;
        }
        cur.e = e;
    }
    public boolean contains(E e) {
        Node cur = dummyHead.next;
        while(cur != null){
            if(cur.e.equals(e)){
                return true;
            }
            cur = cur.next;
        }
        return false;
    }
    @Override
    public String toString() {
        StringBuilder res = new StringBuilder();
//        Node cur = dummyHead.next;
//        while(cur != null) {
//            res.append(cur + "->");
//            cur = cur.next;
//        }
        for(Node cur = dummyHead ; cur != null ; cur = cur.next) {
            res.append(cur.e + "->");
        }
        res.append("NULL");
        return res.toString();
    }

    public E remove(int index) {
        if(index < 0 || index > size) {
            throw new IllegalArgumentException("Get 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;
    }
    public E removeFirst() {
        return remove(0);
    }
    public E removrLast() {
        return remove(size - 1);
    }
}

链表栈 LinkedListStack：

package Date_pacage;

public class LinkedListStack<E> implements Stack<E> {
    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);
    }
    private LinkedList<E> list;
    public LinkedListStack() {
        list = new LinkedList<>();
    }
    @Override
    public int getSize() {
        return list.getSize();
    }
    @Override
    public boolean isEmpty() {
        return list.isEmpty();
    }
    @Override
    public void push(E e) {
        list.addFirst(e);
    }
    @Override
    public E pop() {
        return list.removeFirst();
    }
    @Override
    public E peek() {
        return list.getFirst();
    }
    @Override
    public String toString() {
        StringBuilder res = new StringBuilder();
        res.append("Stack: top");
        res.append(list);
        return res.toString();
    }

}

链表队列 LinkedListQueue：

package Date_pacage;

//使用带尾节点的链表
public class LinkedListQueue<E> implements Queue<E> {
    public static void main(String[] args) {
        LinkedListQueue<Integer> linkedList = new LinkedListQueue<>();
        for(int i = 0 ; i < 5 ; i ++) {
            linkedList.enqueue(i);
            System.out.println(linkedList);
        }
        linkedList.enqueue(666);
        System.out.println(linkedList);
        linkedList.dequeue();
        System.out.println(linkedList);
    }
    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();
        }
    }

    private Node head, tail;
    private int size;
    public LinkedListQueue() {
        head = null;
        tail = null;
        size = 0;
    }
    @Override
    public int getSize() {
        return size;
    }
    @Override
    public boolean isEmpty() {
        return size == 0;
    }
    @Override
    public E getFront() {
        if(isEmpty()) {
            throw new IllegalArgumentException("Cannot getFront from an empty queue.");
        }
        return head.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++;
    }
    @Override
    public E dequeue() {
        if(isEmpty()) {
            throw new IllegalArgumentException("Cannot dequeue from an empty queue.");
        }
        Node retNode = head;
        head = head.next;
        retNode.next = null;
        if(head == null) {
            tail = null;
        }
        size--;
        return retNode.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();
    }
}