jian-zhi-offer-09.-yong-liang-ge-zhan-shi-xian-dui-lie.md

剑指 Offer 09. 用两个栈实现队列

class CQueue:

    def __init__(self):
        self.s1 = []
        self.s2 = []


    def appendTail(self, value: int) -> None:
        self.s1.append(value)


    def deleteHead(self) -> int:
        if self.s2:
            return self.s2.pop()
        if not self.s1 :return -1
        while self.s1:
            self.s2.append(self.s1.pop())
        return self.s2.pop()



# Your CQueue object will be instantiated and called as such:
# obj = CQueue()
# obj.appendTail(value)
# param_2 = obj.deleteHead()