三级菜单操作

1.首先是自己写的一个复杂版的，但是好理解

# __author__:'sunmt'

#date: 2018/7/27

china = {
    '山东':{
        '菏泽':['鄄城','郓城'],
        '济南':['开发区','大明湖区']
             },
    '浙江':{
        '杭州':['滨江','西湖','萧山'],
        '温州':['皮革厂','腾和']
    }
}
start= True
province_list = []
city_list = []

while start:
    print("欢迎来到中国地图".center(20,'='))
    for i ,prov in enumerate(china.keys(),1):
        print(i,prov)
        province_list.append(prov)
    print("若要退出请输入q")
    province = input("请输入你要查看的省份编号：").strip()
    if province == 'q'or province == 'Q':
        break
    if province.isdigit():
        province = int(province)
        if province >0 and province <len(province_list)+1:
            while start:
                for j ,cit in enumerate(china[province_list[province-1]].keys(),1):
                    print(j,cit)
                    city_list.append(cit)
                print("输入q退出，输入b返回上一层".center(20,'='))
                city_num = input("请输入你要查看的城市编号：").strip()
                if city_num == 'q' or city_num == 'Q':
                    start = False
                elif city_num == 'b' or city_num == 'B':
                    del city_list[:]
                    del province_list[:]
                    break
                elif city_num.isdigit():
                    city_num = int(city_num)
                    if city_num > 0 and city_num < len(city_list) + 1:
                        while start:
                            for county in china[province_list[province-1]][city_list[city_num-1]]:
                                print(county)
                            print("输入q退出，输入b返回上一层".center(20,'='))
                            play = input("请输入你的操作：").strip()
                            if play == 'q' or play == 'Q':
                                start = False
                            elif play == 'b' or play == 'B':
                                del city_list[:]
                                break
                            else:
                                print("输入错误".center(20,'='))






                    else:
                        print("城市编号输入错误".center(50,'='))
                else:
                    print("输入错误".center(20,'='))

        else:
            print("省份编号输入错误".center(20,'='))
    else:
        print("数字输入错误".center(20,'='))


2.学了文件操作后写了一个简单版的



with open('省市县', 'r', encoding='utf-8') as f:   #把三级菜单放在‘省市县文件中’

    china = f.read()
    china = eval(china)  #将字符串格式转换成字典格式

current_dic = china

parent_list = []

while True:
    for key in current_dic:
        print(key)
    choice = input("请输入：").strip()
    if choice in current_dic:
        parent_list.append(current_dic)
        current_dic = current_dic[choice]

    elif choice == 'b' or choice == 'B':
        if parent_list:
            current_dic = parent_list.pop()
        else:
            print("已到最顶层")
    elif choice == 'q' or choice == 'Q':
        break
    else:
        print("无此项")