题解 | #【模板】队列#

from re import split
class Queue: #写一个类，用来模拟队列的进队、出队、查看队首数据的操作
    def __init__(self) -> None:
	#定义一个数组，用来存储数据
        self.items = []

    def push(self,item):
        self.items.append(int(item))
    
    def pop(self):
        return self.items.pop(0)
    
    def front(self):
        return self.items[0]

    def size(self):
        return len(self.items)

s = Queue()
num = input()
for i in range(int(num)):
    b = input()
    if b.split()[0] == 'push':
        c = b.split()[1]
        s.push(c)
    elif b == 'pop':
        if s.size() == 0:
            print("error")
        else:
            print(s.pop())
    if b == "front":
        if s.size() == 0:
            print("error")
        else:
            print(s.front())