day2-三级菜单---改良版

再也不想看之前的low代码了。。。确实~~~~ 代码量简化，high了

#!/usr/bin/env python

data = {
    '北京': {
        "昌平": {
            "望京1": {"奔驰", "默默"},
            "国贸2": ("cicc", "HP"),
        },
        "朝阳": {
            "望京1": {"奔驰", "默默"},
            "国贸1": ("cicc", "HP"),
        },
    },
    '山东': {
        "昌平": {
            "望京1": {"奔驰", "默默"},
            "国贸2": ("cicc", "HP"),
        },
        "朝阳": {
            "望京2": {"奔驰", "默默"},
            "国贸2": ("cicc", "HP"),
        },
    },
    '广东': {
        "昌平": {
            "望京1": {"奔驰", "默默"},
            "国贸2": ("cicc", "HP"),
        },
        "朝阳": {
            "望京3": {"奔驰", "默默"},
            "国贸4": ("cicc", "HP"),
        },
    },
}
current_layer = data
layerlist = list()
while True:
    for i in current_layer:  #去重复，定义一个打印，变量是current_layer
        print(i)
    choice = input("选择进入,按b返回,按q退出>>:")
    if choice in current_layer:
        try:  #防止读取到最后一层报错
            layerlist.append(current_layer)
            current_layer = current_layer[choice]
        except TypeError:
            pass  # 如果最后一层，则保持当层不变
        continue
    elif choice.lower() == 'b':
        try:#防止回退到最开始一层报错
            current_layer = layerlist.pop()
        except IndexError:
            pass#如果第一层，则保持当层不变
        continue
    elif choice.lower() == 'q':
        exit("bye~~")