1.雙端隊(duì)列類設(shè)計(jì)

public static class Node<T>{
       public T value;
       public Node<T> last;
       public Node<T> next;
       public Node(T data){
           value = data;
       }
   }
   //雙向隊(duì)列
   public static class DoubleEndsQueue<T>{
       public Node<T> head;
       public Node<T> tail;
       //1.從頭部增加節(jié)點(diǎn)
       public void addFromHead(T value){
           Node<T> cur = new Node<>(value);
           if(head == null){
               head = cur;
               tail = cur;
           }else {
               cur.next = head;
               head.last = cur;
               head = cur;
           }
       }
       //2.從尾部增加節(jié)點(diǎn)
       public void addFromTail(T value){
           Node<T> cur = new Node<>(value);
           if(head == null){
               head = cur;
               tail = cur;
           }else {
               tail.next = cur;
               cur.last = tail;
               tail = cur;
           }
       }
       //3.從頭部刪除節(jié)點(diǎn),并返回刪除節(jié)點(diǎn)的值
       public T deleteFromHead(){
           //(1)判斷是否為空
           if(head == null)
               return null;
           Node<T> cur = head;
           //(2)判斷是否只有一個(gè)節(jié)點(diǎn)
           if(head == tail){
               head = null;
               tail = null;
           }else {
               head = head.next;
               cur.next = null;
               head.last = null;
           }
           return cur.value;
       }
       //4.從尾部刪除節(jié)點(diǎn),并返回刪除節(jié)點(diǎn)的值
       public T deleteFromTail(){
           //(1)判斷是否為空
           if(head == null)
               return null;
           Node<T> cur = head;
           //(2)判斷是否只有一個(gè)節(jié)點(diǎn)
           if(head == tail){
               head = null;
               tail = null;
           }else {
              tail = tail.last;
              cur.last = null;
              tail.next = null;
           }
           return cur.value;
       }
       public boolean isEmpty(){
           return head == null;
       }
   }

2.棧的實(shí)現(xiàn)

• 頭部進(jìn)，頭部出

private static class DoubleQueueStack<T>{
       private DoubleEndsQueue<T> queue;

       public DoubleQueueStack() {
           queue = new DoubleEndsQueue<T>();
       }
       public void push(T value){
           queue.addFromHead(value);
       }
       public T pop(){
           return queue.deleteFromHead();
       }
       public boolean isEmpty(){
           return queue.isEmpty();
       }
   }

3.隊(duì)列的實(shí)現(xiàn)

• 頭部進(jìn)，尾部出

private static class DoubleQueue<T>{
       private DoubleEndsQueue<T> queue;
       public DoubleQueue(){
           queue = new DoubleEndsQueue<T>();
       }
       public void push(T value){
           queue.addFromHead(value);
       }
       public T pop(){
           return queue.deleteFromTail();
       }
       public boolean isEmpty(){
           return queue.isEmpty();
       }
   }