LeetCode -- Implement Queue using Stacks

public class Queue {
    public Queue(){
        _s1 = new Stack<int>();
        _s2 = new Stack<int>();
    }
    private Stack<int> _s1 ;
    private Stack<int> _s2;
    // Push element x to the back of queue.
    public void Push(int x) {
        _s2.Push(x);
    }
    
    // Removes the element from front of queue.
    public void Pop() {
        while(_s2.Count > 0){
            _s1.Push(_s2.Pop());
        }
        _s1.Pop();
        while(_s1.Count > 0)
        {
            _s2.Push(_s1.Pop());
        }
    }


    // Get the front element.
    public int Peek() {
		while(_s2.Count > 0){
			_s1.Push(_s2.Pop());
		}
		
        var n = _s1.Peek();
		while(_s1.Count > 0){
			_s2.Push(_s1.Pop());
		}
        return n;
    }


    // Return whether the queue is empty.
    public bool Empty() {
        return _s2.Count == 0;
    }
}

LeetCode -- Implement Queue using Stacks

原文：http://blog.csdn.net/lan_liang/article/details/48379771