站在Java的角度看LinkedList

站在Java的角度看，玩队列不就是玩对象引用对象嘛！

public class LinkedList<E> implements List<E>, Deque<E> {
  Node<E> first;
  Node<E> last;
  int size;

  public boolean add(E e) {
        final Node<E> l = last;
        final Node<E> newNode = new Node<>(l, e, null);
        last = newNode;
        if (l == null)
            first = newNode;
        else
            l.next = newNode;
        size++;
        modCount++;
        return true;
    }

  private static class Node<E> {
        E item;
        Node<E> next;
        Node<E> prev;

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

单链表反转：

/**
     * 递归，在反转当前节点之前先反转后续节点
     */
    public static Node reverse(Node head) {
        if (null == head || null == head.getNextNode()) {
            return head;
        }
        Node reversedHead = reverse(head.getNextNode());
        head.getNextNode().setNextNode(head);
        head.setNextNode(null);
        return reversedHead;
    }  

    /**
     * 遍历，将当前节点的下一个节点缓存后更改当前节点指针
     *
     */
    public static Node reverse2(Node head) {
        if (null == head) {
            return head;
        }
        Node pre = head;
        Node cur = head.getNextNode();
        Node next;
        while (null != cur) {
            next = cur.getNextNode();
            cur.setNextNode(pre);
            pre = cur;
            cur = next;
        }
        //将原链表的头节点的下一个节点置为null，再将反转后的头节点赋给head
        head.setNextNode(null);
        head = pre;  

        return head;
    }

对于数组问题，一般我们要新建数组，必要时移动下标