【數據結構】【線性表】鏈表

1 引言

鏈表是一種鏈式存儲的線性表，所有元素的內存地址不一定是連續的。

2 接口

/**
 * @Description: 線性表接口
 * @Auther: zhurongsheng
 * @Date: 2020/4/22 23:26
 */
public interface ZrsList<E> {

    /**
     * 元素數量
     */
    int size();

    /**
     * 是否爲空
     */
    boolean isEmpty();

    /**
     * 是否包含
     */
    boolean contains(E element);

    /**
     * 添加元素
     */
    void add(E element);

    /**
     * 返回index位置對應的元素
     */
    E get(int index);

    /**
     * 設置index位置的元素，返回原來的元素
     */
    E set(int index, E element);

    /**
     * 在index位置添加元素
     */
    void add(int index, E element);

    /**
     * 刪除index對應的元素
     */
    E remove(int index);

    /**
     * 查看元素的位置
     */
    int indexOf(E element);

    /**
     * 清除所有元素
     */
    void clear();
}

3 實現類

/**
 * @Description:
 * @Auther: zhurongsheng
 * @Date: 2020/4/25 13:55
 */
public class ZrsLinkedList<E> implements ZrsList<E> {

    private int size;

    private Node<E> first;

    private Node<E> last;


    public ZrsLinkedList() {

    }


    @Override
    public int size() {
        return size;
    }

    @Override
    public boolean isEmpty() {
        return size == 0;
    }

    @Override
    public boolean contains(E element) {
        return false;
    }

    @Override
    public void add(E element) {
        Node<E> lastNode = last;
        Node<E> newNode = new Node<>(element, null, lastNode);
        last = newNode;
        if (first == null)
            first = newNode;
        else
            lastNode.next = newNode;
        size++;
    }

    @Override
    public E get(int index) {
        rangeCheck(index);
        return node(index).element;
    }

    private void rangeCheck(int index) {
        if (index >= 0 && index <= size - 1) {
            return;
        }
        throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
    }

    private void rangeCheckForAdd(int index) {
        if (index >= 0 && index <= size) {
            return;
        }
        throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
    }

    private String outOfBoundsMsg(int index) {
        return "Index: " + index + ", Size: " + size;
    }

    @Override
    public E set(int index, E element) {
        rangeCheck(index);
        Node<E> node = node(index);
        E oldValue = node.element;
        node.element = element;
        return oldValue;
    }

    @Override
    public void add(int index, E element) {
        rangeCheckForAdd(index);
        if (index == size) {
            add(element);
        } else {
            Node<E> node = node(index);
            Node<E> prevNode = node.prev;
            Node<E> newNode = new Node<>(element, node, prevNode);
            prevNode.next = newNode;
            node.prev = newNode;
            size++;
        }
    }

    @Override
    public E remove(int index) {
        rangeCheck(index);
        Node<E> node = node(index);
        E oldVal = node.element;
        Node<E> nextNode = node.next;
        Node<E> prevNode = node.prev;

        if (prevNode == null) {
            first = nextNode;
        } else {
            prevNode.next = nextNode;
            node.prev = null;
        }

        if (nextNode == null) {
            last = prevNode;
        } else {
            nextNode.prev = prevNode;
            node.next = null;
        }

        node.element = null;
        size--;
        return oldVal;
    }

    @Override
    public int
    indexOf(E element) {
        int index = 0;
        if (element == null) {
            for (Node<E> node = first; node != null; node = node.next) {
                if (node.element == null) return index;
                index++;
            }
        } else {
            for (Node<E> node = first; node != null; node = node.next) {
                if (node.element.equals(element)) return index;
                index++;
            }
        }
        return -1;
    }


    private Node<E> node(int index) {
        if (index < size / 2) {
            Node<E> x = first;
            for (int i = 0; i < index; i++) {
                x = x.next;
            }
            return x;
        } else {
            Node<E> x = last;
            for (int i = size - 1; i > index; i--) {
                x = x.prev;
            }
            return x;
        }
    }


    @Override
    public void clear() {

        for (Node<E> node = first; node != null; ) {
            Node<E> next = node.next;
            node.element = null;
            node.next = null;
            node.prev = null;
            node = next;
        }

        first = null;
        last = null;
        size = 0;

    }

    private static class Node<E> {

        private E element;
        Node<E> next;
        Node<E> prev;

        private Node(E element, Node<E> next, Node<E> prev) {
            this.element = element;
            this.next = next;
            this.prev = prev;
        }

    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("[");
        int index = 0;
        for (Node<E> node = first; node != null; node = node.next) {
            if (index == 0) {
                sb.append(node.element);
            } else {
                sb.append(", ").append(node.element);
            }
            index++;
        }
        sb.append("]");
        return sb.toString();
    }


}

4 測試

/**
 * @Description:
 * @Auther: zhurongsheng
 * @Date: 2020/4/25 15:05
 */
public class ListTest {

    public static void main(String[] args) {
        testZrsList();
        System.out.println("################");
        testJdkList();
    }

    private static void testJdkList() {

        List<Integer> list = new LinkedList<>();
        for (int i = 0; i < 10; i++) {
            list.add(i,i);
        }
        list.add(5,50);
        System.out.println(list.toString());
        list.remove(5);
        System.out.println(list.toString());
        list.remove(0);
        System.out.println(list.toString());
        list.remove(list.size()-1);
        System.out.println(list.toString());
    }

    private static void testZrsList(){
        ZrsLinkedList<Integer> zrsList = new ZrsLinkedList<>();
        for (int i = 0; i < 10; i++) {
            zrsList.add(i,i);
        }
        zrsList.add(5,50);
        System.out.println(zrsList.toString());
        zrsList.remove(5);
        System.out.println(zrsList.toString());
        zrsList.remove(0);
        System.out.println(zrsList.toString());
        zrsList.remove(zrsList.size()-1);
        System.out.println(zrsList.toString());
    }

}

5 結果