三级菜单的三个版本

1.这是我们通过一般方式进行的，就是按照正常的思路来写的，一步一步走

 1 #_author:sangshijia
 2 #date:2016/8/24
 3 menu_map={
 4     "河南":{
 5         "郑州":["新密","登封","中牟"],
 6         "洛阳":["汝阳","伊川","嵩县"],
 7         "南阳":["西峡","方城","内乡"],
 8     },
 9     "河北":{
10         "保定":["顺平","曲阳","徐水"],
11         "邢台":["临城","清河","新河"],
12         "邯郸":["广平","鸡泽","肥乡"],
13     },
14     "安徽":{
15         "合肥":["长丰","肥东","肥西"],
16         "毫州":["蒙城","利辛","涡阳"],
17         "滁州":["凤阳","来安","定远"],
18     },
19 
20 }
21 flag=True
22 while True:
23     for key in menu_map:
24         print(key)
25     choice=input("1，请输入省份，b返回上一级目录，d删除省份>>>:").strip()
26     if choice =="b":
27         break
28         print("返回上一级目录")
29     if choice =="d":
30         choice_del=input("请输入需要删除的省份：").strip()
31         del menu_map[choice_del]
32     elif choice in menu_map:
33         while True:
34             for key2 in menu_map[choice]:
35                 print(key2)
36             choice2 = input("2，请输入市，b返回上一级目录，d删除市>>>:").strip()
37             if choice2 =="b":
38                 break
39                 print("返回上一级目录")
40             if choice2 =="d":
41                 choice_del = input("请输入需要删除的市：").strip()
42                 del menu_map[choice][choice_del]
43             elif choice2 in menu_map[choice]:
44                 while True:
45                     for key3 in menu_map[choice][choice2]:
46                         print(key3)
47                     choice3=input("3，请输入县，b返回上一级目录，d删除县>>>:").strip()
48                     if choice3 =="b":
49                         break
50                         print("返回上一级目录")
51                     if choice3 =="d":
52                         choice_del = input("请输入需要删除的县：").strip()
53                         del menu_map[choice][choice2][choice3]
54                     elif choice3 in menu_map[choice][choice2]:
55                         print("last level")
56                     elif choice3 not in menu_map[choice][choice2]:
57                         choice3 = input("请输入添加的县>>：").strip()
58                         menu_map[choice][choice2][choice3]={}
59             elif choice2 not in menu_map[choice]:
60                 choice2 = input("请输入添加的市>>：").strip()
61                 menu_map[choice][choice2] = {}
62     elif choice not in menu_map:
63         choice = input("请输入添加的省>>：").strip()
64     menu_map[choice] = {}

2.这是简便后的，代码少了很多，就是把上一部分的一些重复代码简化而成的

 1 #_author:sangshijia
 2 #date:2016/8/26
 3 menu={
 4     "河南":{
 5         "郑州":["新密","登封","中牟"],
 6         "洛阳":["汝阳","伊川","嵩县"],
 7         "南阳":["西峡","方城","内乡"],
 8     },
 9     "河北":{
10         "保定":["顺平","曲阳","徐水"],
11         "邢台":["临城","清河","新河"],
12         "邯郸":["广平","鸡泽","肥乡"],
13     },
14     "安徽":{
15         "合肥":["长丰","肥东","肥西"],
16         "毫州":["蒙城","利辛","涡阳"],
17         "滁州":["凤阳","来安","定远"],
18     },
19 
20 }
21 import sys
22 current_layer=menu
23 parent_layers=[]
24 while True:
25     for key in current_layer:
26         print(key)
27     choice=input(">>>:").strip()
28     if len(choice)==0:continue
29     if choice in current_layer:
30         parent_layers.append(current_layer)
31         current_layer=current_layer[choice]
32     elif choice=="b":
33         if parent_layers:
34             current_layer=parent_layers.pop()
35     else:
36         print("无此项")

3.通过文件把menu_map中的内容存储到新建的一个文件aaa里面，这样就可以把menu_map这一段内容注释掉，通过调用新文件aaa来执行，同时呢，也熟悉了文件的一些操作

,同时也添加了增加和删除这2个功能，但是我只能用老方法来实现文件的加入，

 1 #_author:sangshijia
 2 #date:2016/8/24
 3 #f=open('menu_map',encoding='utf8')
 4 # menu_map={
 5 #     "河南":{
 6 #         "郑州":["新密","登封","中牟"],
 7 #         "洛阳":["汝阳","伊川","嵩县"],
 8 #         "南阳":["西峡","方城","内乡"],
 9 #     },
10 #     "河北":{
11 #         "保定":["顺平","曲阳","徐水"],
12 #         "邢台":["临城","清河","新河"],
13 #         "邯郸":["广平","鸡泽","肥乡"],
14 #     },
15 #     "安徽":{
16 #         "合肥":["长丰","肥东","肥西"],
17 #         "毫州":["蒙城","利辛","涡阳"],
18 #         "滁州":["凤阳","来安","定远"],
19 #     },
20 #
21 # }
22 # new_menu=str(menu_map)
23 # f=open("aaa","w",encoding='utf8')
24 # f.write(new_menu)
25 # f.close()
26 f=open("aaa","r",encoding='utf8')
27 menu_map=f.read()
28 menu_map=eval(menu_map)
29 flag=True
30 while True:
31     for key in menu_map:
32         print(key)
33     choice=input("1，请输入省份，b表示返回上一级目录，d表示删除省份>>>:").strip()
34     if choice =="b":
35         break
36         print("返回上一级目录")
37     if choice =="d":
38         choice_del=input("请输入需要删除的省份：").strip()
39         del menu_map[choice_del]
40     elif choice in menu_map:
41         while True:
42             for key2 in menu_map[choice]:
43                 print(key2)
44             choice2 = input("2，请输入市，b表示返回上一级目录，d表示删除市>>>:").strip()
45             if choice2 =="b":
46                 break
47                 print("返回上一级目录")
48             if choice2 =="d":
49                 choice_del = input("请输入需要删除的市：").strip()
50                 del menu_map[choice][choice_del]
51             elif choice2 in menu_map[choice]:
52                 while True:
53                     for key3 in menu_map[choice][choice2]:
54                         print(key3)
55                     choice3=input("3，请输入县，b表示返回上一级目录，d表示删除县>>>:").strip()
56                     if choice3 =="b":
57                         break
58                         print("返回上一级目录")
59                     if choice3 =="d":
60                         choice_del = input("请输入需要删除的县：").strip()
61                         del menu_map[choice][choice2][choice3]
62                     elif choice3 in menu_map[choice][choice2]:
63                         print("last level")
64                     elif choice3 not in menu_map[choice][choice2]:
65                         choice3 = input("请输入添加的县>>：").strip()
66                         menu_map[choice][choice2][choice3]={}
67             elif choice2 not in menu_map[choice]:
68                 choice2 = input("请输入添加的市>>：").strip()
69                 menu_map[choice][choice2] = {}
70     elif choice not in menu_map:
71         choice = input("请输入添加的省>>：").strip()
72     menu_map[choice] = {}