Python学习笔记-三级菜单优化（四）

menu = {
    ‘北京‘ : {
        ‘昌平‘ : {
            ‘沙河‘ : ["test1","test2"],
            ‘天通苑‘ : ["链家","我爱我家"],
        },
        ‘朝阳‘ : {
            "望京" : ["奔驰","陌陌"],
            "国贸" : ["CICC","HP"],
            "东直门" : ["Advent","飞信"],
        },
        ‘海淀‘ : {},
     },
    ‘河北‘ : {},
    ‘上海‘ : {},
}
exit_flag = False
current_layer = menu
layer = [menu]
while not exit_flag:
    for k in current_layer:
        print(k)
    choice = input(">>>:").strip()
    if choice == ‘b‘:
        current_layer = layer[-1]
        layer.pop()
    elif choice == ‘q‘:
        exit()
    elif choice not in current_layer:continue
    else:
        layer.append(current_layer)
        current_layer = current_layer[choice]