算法（Algorithms）第4版 练习 1.3.41

方法实现：

    //1.3.41
    public Queue(Queue<Item> q) {

        Queue<Item> result = new Queue<Item>();

        int size = q.size();
        for(int i = 0; i < size; i++) {
            Item item= q.dequeue();
            q.enqueue(item);
            result.enqueue(item);
        }

        this.first = result.first;
        this.last = result.last;
        this.n = result.size();

    }

测试：

//1.3.41
        Queue<String> r = new Queue<String>(queue);
        StdOut.println("After copy");
        StdOut.print("Left on queue r: ");
        for (String s : r) {
            StdOut.print(s + " ");
        }
        StdOut.println();
        StdOut.print("Left on queue queue: ");
        for (String s : queue) {
            StdOut.print(s + " ");
        }
        StdOut.println();

        r.dequeue();
        StdOut.println("After r.dequeue");
        StdOut.print("Left on queue r: ");
        for (String s : r) {
            StdOut.print(s + " ");
        }
        StdOut.println();
        StdOut.print("Left on queue queue: ");
        for (String s : queue) {
            StdOut.print(s + " ");
        }
        StdOut.println();

结果：

After copy
Left on queue r: to be or not
Left on queue queue: to be or not
After r.dequeue
Left on queue r: be or not
Left on queue queue: to be or not