题解 | #用两个栈实现队列#

class Solution:
    def __init__(self):
        self.stack1 = []
        self.stack2 = []
    def push(self, node):
        # write code here
        self.stack1.append(node)

    def pop(self):
        global ret
        if self.stack2:
            ret=self.stack2.pop()
        else:
            if self.stack1:
                for i in range(0,len(self.stack1)):
                    self.stack2.append(self.stack1.pop())
                ret=self.stack2.pop() 
        return ret