232.用栈实现队列 inStack; Deque outStack; public MyQueue() { inStack = new ArrayDeque(); outStack = new ArrayDeque(); } 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(); */