三级菜单

需求：

• 可依次选择进入各子菜单
• 可从任意一层往回退到上一层
• 可从任意一层退出程序

 1 #!/usr/bin/env python3
 2 #-*- coding:utf-8 -*-
 3 ‘‘‘
 4 Time:2018/5/3 16:23
 5 File:三层菜单
 6 Author:ly
 7 ‘‘‘
 8 menu = {
 9     ‘北京‘:{
10         ‘海淀‘:{
11             ‘五道口‘:{
12                 ‘soho‘:{},
13                 ‘网易‘:{},
14                 ‘google‘:{}
15             },
16             ‘中关村‘:{
17                 ‘爱奇艺‘:{},
18                 ‘汽车之家‘:{},
19                 ‘youku‘:{},
20             },
21             ‘上地‘:{
22                 ‘百度‘:{},
23             },
24         },
25         ‘昌平‘:{
26             ‘沙河‘:{
27                 ‘老男孩‘:{},
28                 ‘北航‘:{},
29             },
30             ‘天通苑‘:{},
31             ‘回龙观‘:{},
32         },
33         ‘朝阳‘:{},
34         ‘东城‘:{},
35     },
36     ‘上海‘:{
37         ‘闵行‘:{
38             "人民广场":{
39                 ‘炸鸡店‘:{}
40             }
41         },
42         ‘闸北‘:{
43             ‘火车站‘:{
44                 ‘携程‘:{}
45             }
46         },
47         ‘浦东‘:{},
48     },
49     ‘山东‘:{},
50 }
51 Current_layer = menu # 当前层
52 
53 Next_layer = [ menu ] # 下一层
54 
55 exit_flag = False
56 
57 while not exit_flag:
58     for i in Current_layer:59         print(i)
60     choice = input("请输入你的选择|B返回|Q退出：").strip()
61 
62     if choice in Current_layer: # 如果在当前层里
63         Next_layer.append(Current_layer) # 则将当前层添加到下一层
64         Current_layer = Current_layer[choice]
65 
66     if choice == ‘b‘.casefold():
67         if len(Next_layer) == 0:
68             continue
69         Current_layer = Next_layer[-1] # 取到上一层赋值给当前层
70         Next_layer.pop()
71         # print(Next_layer)
72 
73     if choice== ‘q‘.casefold():
74         exit_flag = True