双向链表实现 栈和队列

package 算法;
/**
 * 双向链表实现 栈和队列
 */
public class test2 {

    public static class Node<T> {
        public T value;
        public Node<T> last;
        public Node<T> next;

        public Node(T data) {
            value = data;
        }
    }
    //双向链表实现栈
    public static class DoubleLinkedStack{
        public test2.Node head = null;

        public void pull(test2.Node value){
            if(head==null){
                //如果没有就直接装
                head = value;
            }else{
                //如果有就把新的换成头
                value.next = head;
                head.last = value;
                head = value;
            }
        }
        public test2.Node pop( ){
            if (head == null) {
                return null;
            }
            test2.Node rt =head;
            if(head.next!=null){
                head.next.last=null;
                head = head.next;
                rt.next =null;
            }else{
                head =null;
            }
            return rt;
        }
    }
    //双向链表实现队列 先进后出
    public static class DoubleLinkedQueue{
        public test2.Node head =null;
        public test2.Node tail = null;

        public void pull(test2.Node value){
            if(head==null){
                //如果没有就直接装
                head = value;
                tail = value;
            }else{
                //如果有就把新的换成头
                head.last = value;
                value.next = head;
                head = value;
            }

        }
        public test2.Node poll( ){
            test2.Node rt = null;
            if (tail != null) {
                rt = tail;
                if (tail.last != null) {
                    tail = tail.last;
                    rt.last = null;
                    tail.next = null;
                }else {
                    tail=null;
                    head =null;
                }
            }
            return rt;
        }
    }

    public static void main(String[] args) {
        //栈测试
        Node n1 = new Node(1);
        Node n2 = new Node(2);
        Node n3 = new Node(3);
        Node n4 = new Node(4);

        DoubleLinkedStack doubleLinkedStack = new DoubleLinkedStack();

        doubleLinkedStack.pull(n1);
        doubleLinkedStack.pull(n2);
        doubleLinkedStack.pull(n3);
        doubleLinkedStack.pull(n4);

        System.out.println(doubleLinkedStack.pop().value);
        System.out.println(doubleLinkedStack.pop().value);
        System.out.println(doubleLinkedStack.pop().value);
        System.out.println(doubleLinkedStack.pop().value);
        System.out.println(doubleLinkedStack.pop());

        doubleLinkedStack.pull(n1);
        System.out.println(doubleLinkedStack.pop().value);
        doubleLinkedStack.pull(n2);
        doubleLinkedStack.pull(n3);
        System.out.println(doubleLinkedStack.pop().value);
        doubleLinkedStack.pull(n4);
        System.out.println(doubleLinkedStack.pop().value);
        System.out.println(doubleLinkedStack.pop().value);
        System.out.println(doubleLinkedStack.pop());


        //队列测试
        DoubleLinkedQueue doubleLinkedQueue = new DoubleLinkedQueue();
        doubleLinkedQueue.pull(n1);
        doubleLinkedQueue.pull(n2);
        doubleLinkedQueue.pull(n3);
        doubleLinkedQueue.pull(n4);
        System.out.println(doubleLinkedQueue.poll().value);
        System.out.println(doubleLinkedQueue.poll().value);
        System.out.println(doubleLinkedQueue.poll().value);
        System.out.println(doubleLinkedQueue.poll().value);
        System.out.println(doubleLinkedQueue.poll());

        doubleLinkedQueue.pull(n1);
        System.out.println(doubleLinkedQueue.poll().value);
        doubleLinkedQueue.pull(n2);
        doubleLinkedQueue.pull(n3);
        System.out.println(doubleLinkedQueue.poll().value);
        doubleLinkedQueue.pull(n4);
        System.out.println(doubleLinkedQueue.poll().value);
        System.out.println(doubleLinkedQueue.poll().value);
        System.out.println(doubleLinkedQueue.poll());

    }
}