LeetCode 232 Implement Queue using Stacks

Implement 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 only

push
to top

,

peek/pop from top

,

size

,
and

is 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).

就是这么麻烦，暂时没找到捷径。
代码如下：

class MyQueue {
Stack<Integer> stackFront = new Stack<Integer>();
Stack<Integer> stackBack = new Stack<Integer>();

// Push element x to the back of queue.
public void push(int x) {
stackBack.push(x);
}

// Removes the element from in front of queue.
public void pop() {
if (!stackFront.isEmpty()) stackFront.pop();
else {
while (!stackBack.isEmpty()) stackFront.push(stackBack.pop());
stackFront.pop();
}
}

// Get the front element.
public int peek() {
if (!stackFront.isEmpty())  return stackFront.peek();
else {
while (!stackBack.isEmpty()) stackFront.push(stackBack.pop());
return stackFront.peek();
}
}

// Return whether the queue is empty.
public boolean empty() {
return stackBack.empty() && stackFront.empty();
}
}