题解 | 【模板】栈

import sys

class Stack():
    def __init__(self) -> None:
        self.item = []
    def push(self, x):
        self.item.append(x)
    def pop(self):
        if self._is_empty():
            print("error")
        else:
            print(self.item[-1])
            self.item.pop()
    def top(self):
        if self._is_empty():
            print("error")
        else:
            print(self.item[-1])
    def _is_empty(self):
        return True if len(self.item) == 0 else False

my_stack =  Stack()
n = int(input())

for i in range(n):
    command = input().split()
    if command[0] == "push":
        my_stack.push(command[1])
    elif command[0] == "pop":
        my_stack.pop()
    elif command[0] == "top":
        my_stack.top()