剑指offer-用两个栈实现队列05

class Solution:
    def __init__(self):
        self.stackpush=[]
        self.stackpop=[]
    def push(self, node):
        # write code here
        self.stackpush.append(node)
    def pop(self):
        # return xx
        if len(self.stackpop)==0:
            while len(self.stackpush) is not 0:
                self.stackpop.append(self.stackpush.pop(-1))
        else:
            return self.stackpop.pop(-1)
        return self.stackpop.pop(-1)

思路：设置两个栈。stackpush用于入队列，stackpop用于出队列，当栈stackpop不为空时，直接出队列。当stackpop为空时，把stackpush出栈，stackpop入栈。直到stackpush为空，之后再出队列栈，完成出队列