书山有路勤为径，学海无涯苦作舟

"""用两个栈来实现一个队列,完成队列的push和pop操作""" class Solution: def __init__(self): self.stack_a = [] self.stack_b = [] def push(self, item): self.stack_a.append(item) def pop1(self): # b中有数据 if self.stack_b: