标签：nod 题目 tail his private 出队 一个 other span
question:
Copy a queue. Create a new constructor so that
Queue<Item> r = new Queue<Item>(q);makes r a reference to a new and independent copy of the queue q. You should be able to push and pop from either q or r without influencing the other. Hint: Delete all of the elements from q and add these elements to both q and r.
answer:
//要注意queue的特性只能尾enqueue，头dequeue，且一次只能对一个元素进行操作
//不过题目中给的提示已经很明显了
import edu.princeton.cs.algs4.*; public class CopyQueue<Item> { private class Node { Item item; Node next; } private Node head; private Node tail; private int N; public CopyQueue() { head = null; tail = null; N = 0; } public CopyQueue(CopyQueue<Item> queue)//注意CopyQueue<Item> { head = null; int size = queue.size(); while(size > 0)//此题关键所在 { Item item = queue.dequeue(); this.enqueue(item); queue.enqueue(item); size--; } } public int size() { return N; } public void enqueue(Item item)//入队 { Node node = new Node(); node.item = item; node.next = null; if(head == null) { N++; tail = head = node; return; } N++; tail.next = node; tail = node; } public Item dequeue()//出队 { if(N == 0) { return null; } Item item = head.item; head = head.next; N--; return item; } public static void main(String[] args) { CopyQueue<String> q1 = new CopyQueue<String>(); q1.enqueue("w"); q1.enqueue("j"); q1.enqueue("c"); CopyQueue<String> q2 = new CopyQueue<String>(q1); for(int i = 0; i < 3; i++) { StdOut.print("q1\t" + q1.dequeue()); StdOut.print("\tq2\t" + q2.dequeue() + "\n"); } } }
标签：nod 题目 tail his private 出队 一个 other span
原文地址：https://www.cnblogs.com/w-j-c/p/9083804.html
