Stack with Two Queues (Or one queue)

这应该是一道老题了。我有些小疑问
通常的解法都要判断queue的size.

1. public void Push(T val) { queLower.Enqueue(val); }

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1. public  T Pop()
   
2.     {
   
3. 
   
4.         if (queLower.Count == 0 )
   
5.         {
   
6.             Console.Write("Stack is empty!");
   
7.             return default(T);
   
8. 
   
9.          }
   
10.         if (queLower.Count > 0)
    
11.         {
    
12.             for (int i = 0; i < queLower.Count - 1;i++ )
    
13.             {
    
14.                 queLower.Enqueue(queLower.Dequeue ());
    
15.            }
    
16.                     }
    
17. 
    
18.         return queLower.Dequeue();
    
19. 
    
20.     }

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如何不用queue.count或queue.isempty()来实现？ (该疑问源自这个帖子：http://www.careercup.com/question?id=3185682 有个人说他在微软技术面时候不让使用queue.count)
引用自该帖子：
I got the same question during a Microsoft technical screen and the guy is like I don't want you to use a count(q.Count) on the queue! Nor to check for queue.isEmtpy(). So my solution relied on catching the exception and handling it and I had a slight bug in my implementation which I discovered but wasn't able to fix. Guess what.. reject! We think the world is sane and we are programming for objects/collection and can count them, apparently we can't :)

数组队列。数组size为n，但只保存n-1个元素。这样空head==(rear+1)%n，满head==(rear+2)%n