1 city = {
 2     "江苏省": {
 3         "南京市": {
 4             "栖霞区": ["aa", "bb"],
 5             "顺义区": ["cc", "dd"],
 6             "普陀区": ["ee", "ff"]
 7         },
 8         "南通市": {
 9             "通州区": ["gg", "hh"],
10             "港闸区": ["ii", "jj"],
11             "崇川区": ["kk", "ll"]
12         },
13     },
14     "浙江省": {
15         "杭州市": {
16             "A区": ["mm", "nn"],
17             "B区": ["oo", "pp"]
18         },
19         "温州市": {
20             "C区": ["qq", "rr"],
21             "D区": ["ss", "tt"]
22         }
23     }
24 }
25 current_layer = city
26 layers = []
27 while True:
28     print("欢迎来到省市区信息管理系统".center(50, "*"))
29     for layer in current_layer:
30         print(layer)
31     choice = input("请输入你要查看的省市区信息,返回上一级按b，退出按q").strip()
32     # 查看
33     if choice in current_layer:
34         layers.append(current_layer)
35         current_layer = current_layer[choice]
36     elif choice == "b":
37         current_layer = layers.pop()
38     elif choice == "q":
39         break
40     else:
41         print("到底了！")