无聊题

class MyStack {
    private ArrayDeque<Integer> queue1;
    private ArrayDeque<Integer> queue2;

    /** Initialize your data structure here. */
    public MyStack() {
        queue1 = new ArrayDeque<Integer>();
        queue2 = new ArrayDeque<Integer>();
    }
    
    /** Push element x onto stack. */
    public void push(int x) {
        queue1.push(x);
    }
    
    /** Removes the element on top of the stack and returns that element. */
    public int pop() {
        int size1 = queue1.size();
        for(int i=0; i < size1 - 1;i++){
            queue2.push(queue1.pollLast());
        }
        int ret = queue1.pop();
        for(int i=0; i < size1 -1;i++){
            queue1.push(queue2.pollLast());
        }
        return ret;

    }
    
    /** Get the top element. */
    public int top() {
        int size1 = queue1.size();
        for(int i=0; i < size1 - 1;i++){
            queue2.push(queue1.pollLast());
        }
        int ret = queue1.pop();
        queue2.push(ret);
        for(int i=0; i < size1 ;i++){
            queue1.push(queue2.pollLast());
        }
        return ret;
    }
    
    /** Returns whether the stack is empty. */
    public boolean empty() {
        return queue1.isEmpty();
    }
}

/**
 * Your MyStack object will be instantiated and called as such:
 * MyStack obj = new MyStack();
 * obj.push(x);
 * int param_2 = obj.pop();
 * int param_3 = obj.top();
 * boolean param_4 = obj.empty();
 */