Java 数据结构与算法系列精讲之环形链表

// Node类
private class Node<E> {

    public E e;  // 元素
    private Node next;  // 下一个节点

    // 构造
    public Node(E e) {
        this.e = e;
        this.next = null;
    }

    @Override
    public String toString() {
        return e.toString();
    }
}

// 插入数据
public void insert(E e) {

    // 创建节点
    Node node = new Node(e);

    if (size == 0) {
        head = node;
        head.next = head;
        tail = head;
    } else {
        tail.next = node;
        node.next = tail;
        tail = node;
    }

    size ++;
}

// 删除元素
public void remove(int index) {

    // 检查索引是否越界
    if (index < 0 || index > size) {
        throw new RuntimeException("Invalid Index");
    }

    // 获取index前一个节点
    Node prev = head;
    for (int i = 0; i < index - 1; i++) {
        prev = prev.next;
    }

    // 删除数据
    Node retNode = prev.next;
    prev.next = retNode.next;

    size --;
}

// main
public static void main(String[] args) {

    // 创建循环链表
    CircularLinkedList<Integer> circularLinkedList = new CircularLinkedList<>();

    // 插入
    for (int i = 0; i < 5; i++) {
        circularLinkedList.insert(i);
        System.out.println(circularLinkedList);
    }

    // 删除
    for (int i = 0; i < 2; i++) {
        circularLinkedList.remove(0);
        System.out.println(circularLinkedList);
    }
}

public class CircularLinkedList<E> {

    // Node类
    private class Node<E> {

        public E e;  // 元素
        private Node next;  // 下一个节点

        // 构造
        public Node(E e) {
            this.e = e;
            this.next = null;
        }

        @Override
        public String toString() {
            return e.toString();
        }
    }

    // 头节点和尾节点
    private Node head = null;
    private Node tail = null;
    private int size;  // 链表大小

    // 构造函数
    public CircularLinkedList() {
        head = new Node(null);
        size = 0;
    }

    // 插入数据
    public void insert(E e) {

        // 创建节点
        Node node = new Node(e);

        if (size == 0) {
            head = node;
            head.next = head;
            tail = head;
        } else {
            tail.next = node;
            node.next = tail;
            tail = node;
        }

        size ++;
    }

    // 删除元素
    public void remove(int index) {

        // 检查索引是否越界
        if (index < 0 || index > size) {
            throw new RuntimeException("Invalid Index");
        }

        // 获取index前一个节点
        Node prev = head;
        for (int i = 0; i < index - 1; i++) {
            prev = prev.next;
        }

        // 删除数据
        Node retNode = prev.next;
        prev.next = retNode.next;

        size --;
    }

    // 链表是否为空
    public boolean isEmpty() {
        return size == 0;
    }

    @Override
    public String toString() {

        StringBuilder builder = new StringBuilder();
        Node cur = head;
        while (cur != tail) {
            builder.append(cur + "->");
            cur = cur.next;
        }
        builder.append(cur);

        return builder.toString();
    }

    // main
    public static void main(String[] args) {

        // 创建循环链表
        CircularLinkedList<Integer> circularLinkedList = new CircularLinkedList<>();

        // 插入
        for (int i = 0; i < 5; i++) {
            circularLinkedList.insert(i);
            System.out.println(circularLinkedList);
        }

        // 删除
        for (int i = 0; i < 2; i++) {
            circularLinkedList.remove(0);
            System.out.println(circularLinkedList);
        }
    }
}