232.用栈实现队列

class MyQueue {Deque<Integer> inStack;Deque<Integer> outStack;public MyQueue() {inStack = new ArrayDeque<Integer>();outStack = new ArrayDeque<Integer>();}public void push(int x) {inStack.push(x);}public int pop() {if(outStack.isEmpty()){in2out();}return outStack.pop();}public int peek() {if(outStack.isEmpty()){in2out();}return outStack.peek();}public boolean empty() {return inStack.isEmpty() && outStack.isEmpty();}private void in2out(){while(!inStack.isEmpty()){outStack.push(inStack.pop());}}
}/*** Your MyQueue object will be instantiated and called as such:* MyQueue obj = new MyQueue();* obj.push(x);* int param_2 = obj.pop();* int param_3 = obj.peek();* boolean param_4 = obj.empty();*/