关于LeetCode中Implement Queue using Stacks一题的理解

题目如下：

mplement the following operations of a queue using stacks.

• push(x) -- Push element x to the back of queue.
• pop() -- Removes the element from in front of queue.
• peek() -- Get the front element.
• empty() -- Return whether the queue is empty.

Notes:

• You must use only standard operations of a stack -- which means onlypush to top,peek/pop from top,size, andis empty operations are valid.
• Depending on your language, stack may not be supported natively. You may simulate a stack by using a list or deque (double-ended queue), as long as you use only standard operations of a stack.
• You may assume that all operations are valid (for example, no pop or peek operations will be called on an empty queue).

class MyQueue {
    private Stack s;
    private Stack temp;
    public MyQueue(){
        s = new Stack<Integer>();
        temp = new Stack<Integer>();
    }
    // Push element x to the back of queue.
    public void push(int x) {
        s.push(x);
    }

    // Removes the element from in front of queue.
    public void pop() {
        if(temp.empty()){
            while(!s.empty()){
                temp.push(s.pop());
            }
        }
        temp.pop();
    }

    // Get the front element.
    public int peek() {
        int result = 0;
        if(temp.empty()){
            while(!s.empty()){
                temp.push(s.pop());
            }
        }
        result = (int)temp.peek();
        return result;
    }
    // Return whether the queue is empty.
    public boolean empty() {
        if(s.empty()&&temp.empty()){
            return true;
        }else{
            return false;
        }
    }
}

    题目的意思就是用栈去实现一个队列，只能用栈的一些基本操作，如pop，push，peek，empty等。还是比较容易实现的，已Accepted的代码在上面。

    这道题也是有Editorial Solution的，地址在这里：https://leetcode.com/articles/implement-queue-using-stacks/ 。里面说了两种方式，比较详细，而且有图，容易理解。