接着上一篇“使用两个队列模拟一个栈”,这里该如何使用两个栈模拟一个队列呢?具体实现如下:
1 public class Queue<E>{ 2 private Stack<E> s1 = null; //s1作为插入栈 3 private Stack<E> s2 = null; //s2作为弹出栈 4 5 public Queue(){ 6 s1 = new Stack<E>(); 7 s2 = new Stack<E>(); 8 } 9 //判断队列是否为空 10 public synchronized boolean isEmpty(){ 11 return s1.isEmpty()&&s2.isEmpty(); 12 } 13 14 //统计队列中元素个数 15 public synchronized int size(){ 16 return s1.size()+s2.size(); 17 } 18 19 //入队列 20 public synchronized void put(E data){ 21 s1.push(data); 22 } 23 24 //出队列(记得要将出完队列 25 public synchronized E pop(){ 26 if(s2.isEmpty()) 27 while(!s1.isEmpty()) 28 s2.push(s1.pop()); 29 return s2.pop(); 30 } 31 }
时间: 2024-10-10 21:41:36