# 一级菜单
def menu1():
    print(‘一级菜单‘.center(40,‘-‘))
    for index1,key1 in enumerate(dic.keys(),1):   # 遍历一级菜单
        print(index1,key1)
        dic_key[str(index1)] = key1
    # print(dic_key)
    choose = input("请选择1级菜单，输入B返回上一级菜单，输入Q退出菜单:")
    if choose == ‘q‘:quit()
    elif choose == ‘b‘:
        print("此处为一级菜单，不能返回")
    elif dic_key.get(choose):
        menu2(dic_key[choose])      # 将二级菜单的key传给函数menu2
    else:
        print("输入有误，请重新输入")


def menu2(choose1):
    print(‘二级菜单‘.center(40, ‘-‘))
    for index2,key2 in enumerate(dic[choose1].keys(),1):      # 遍历二级菜单
        print(index2,key2)
        dic_key[str(index2)] = key2
    choose2 = input("请选择2级菜单，输入B返回上一级菜单，输入Q退出菜单")
    if choose2 == ‘q‘:quit()
    elif choose2 == ‘b‘:
        menu1()
    elif dic_key.get(choose2):
        menu3(choose1,dic_key[choose2])
    else:
        print("输入有误，请重新输入")


def menu3(choose1,choose2):
    print(‘三级菜单‘.center(40, ‘-‘))
    for index3, key3 in enumerate(dic[choose1][choose2].keys(), 1):
        print(index3, key3)
        dic_key[str(index3)] = key3
    choose3 = input("请选择3级菜单，输入B返回上一级菜单，输入Q退出菜单")
    if choose3 == ‘q‘:
        quit()
    elif choose3 == ‘b‘:
        menu2(choose1)
    elif dic_key.get(choose3):
        menu4(choose1,choose2,dic_key[choose3])
    else:
        print("输入有误，请重新输入")


def menu4(choose1,choose2,choose3):
    for index4, vaule in enumerate(dic[choose1][choose2][choose3],1):
        print(index4, vaule)


if __name__ == ‘__main__‘:
    dic =         {
            ‘北京‘: {
                ‘东城‘:
                    {
                        ‘沙河‘: [‘老男孩‘, ‘恋家‘],
                        ‘天通苑‘: [‘手机卖场‘, ‘屌丝吧‘]
                    },
                ‘朝阳‘:
                    {
                        ‘花家地‘: [‘朝阳公园‘, ‘望京soho‘],
                        ‘北小河‘: [‘北小河公园‘, ‘北京中学‘]
                    }
            },
            ‘上海‘: {
                ‘虹桥‘:
                    {
                        ‘虹桥机场‘: [‘超市‘, ‘特产店‘, ‘水吧‘],
                        ‘东方明珠‘: [‘电影院‘, ‘游泳馆‘, ‘餐馆‘]
                    },
                ‘浦东‘:
                    {
                        ‘景秀路‘: [‘世纪公园‘, ‘立交桥‘],
                        ‘中环路‘: [‘鲁迅公园‘, ‘同济大学‘]
                    }
            }
        }
    dic_key = {}
    while True:
        menu1()