代码随想录算法训练营第十天丨232.用栈实现队列，225. 用队列实现栈

232.用栈实现队列

class MyQueue:
    def __init__(self):
        self.stackIn = []
        self.stackOut = []

    def push(self, x: int) -> None:
        self.stackIn.append(x)

    def pop(self) -> int:
        if not self.stackOut:
            while self.stackIn:
                self.stackOut.append(self.stackIn.pop())
        return self.stackOut.pop()

    def peek(self) -> int:
        if not self.stackOut:
            while self.stackIn:
                self.stackOut.append(self.stackIn.pop())
        return self.stackOut[-1]

    def empty(self) -> bool:
        return not self.stackIn and not self.stackOut

225. 用队列实现栈

class MyStack:

    def __init__(self):
        self.queue1 = deque()
        self.queue2 = deque()

    def push(self, x: int) -> None:
        self.queue2.append(x)
        while self.queue1:
            self.queue2.append(self.queue1.popleft())
        self.queue1, self.queue2 = self.queue2, self.queue1

    def pop(self) -> int:
        return self.queue1.popleft()

    def top(self) -> int:
        return self.queue1[0]

    def empty(self) -> bool:
        return not self.queue1