三级菜单

1.比较复杂的写法，但是逻辑很清晰，基本都能看的懂  代码重复多

memu={
    "湖南":{
        "长沙":{
            "浏阳市":{
                "北乡":3434,
                "东乡":1212,
                "南乡":4454,
                "西乡":564
            },
            "宁乡市":{
                "花明楼":678,
                "东湖塘":344,
                "白马桥":98
            },
            "天心区":{
                "金盆岭":768,
                "书院路":456
            },
            "开福区":{
                "伍家岭":234,
                "四方坪":789
            },
            "岳麓区":{
                "橘子洲":6789,
                "洋湖":4567
            }
        },
        "株洲市":{},
        "湘潭市":{},
        "衡阳市":{},
        "邵阳市":{},
        "岳阳市":{},
        "常德市":{},
        "张家界市":{},
        "益阳市":{},
        "永州市":{},
        "怀化市":{},
        "娄底市":{},
        "湘西土家族苗族自治州":{}
    },
    "海南":{
        "海口":{
            "琼山区":{
                 "琼山区景点":123
            }
        },
        "三亚":{
            "亚龙湾":{
                "亚龙湾景点":345
            }
        },
        "儋州":{
                "詹舟":{
                    "詹州景点":1234
                }
        }

    }
}
run_flag=True
while run_flag:        #标志位
    for i in memu:
        print(i)         #遍历打印第一层字典
    province_choices=input("请输入省>>>")
    province_list=memu.keys()
    print(province_list)
    if province_choices in province_list:
        while run_flag:
            for i in memu[province_choices]:
                print(i)
            city_choices=input("请输入市，按b返回上一级，按q退出")
            if city_choices in memu[province_choices]:
                while run_flag:
                    for i in memu[province_choices][city_choices]:
                        print(i)
                    zone_choices=input("请输入县，按b返回上一级，按q退出")
                    if zone_choices in memu[province_choices][city_choices]:
                        while run_flag:
                            for i in memu[province_choices][city_choices][zone_choices]:
                                print(i)
                            town_choices=input("请输入镇，按b返回上一级，按q退出")
                            if town_choices in memu[province_choices][city_choices][zone_choices]:
                                    town_values=memu[province_choices][city_choices][zone_choices][town_choices]
                                    print(town_values)
                            elif town_choices=="q":
                                run_flag=False
                            elif town_choices=="b":
                                pass
                            else:
                                continue
                    elif zone_choices=="q":
                        run_flag=False
                    elif zone_choices=="b":
                        break
                    else:
                        continue
            elif city_choices=="q":
                break
            elif city_choices=="b":
                break
            else:
                continue
    elif province_choices=="q":
        run_flag=False
    else:
        continue

2第二种方法  简单易懂重复代码少

能回退到每一层

current_layer=memu
level=[]
while True:
    for k in current_layer:
        print(k)
    choices=input("请输入>>或者q退出，或者b返回上一层")
    if choices in current_layer:
        level.append(current_layer)
#        print(level)
        current_layer=current_layer[choices]
    elif choices=="b":
        if len(level)>0:
            current_layer=level.pop()
        else:
            print("已经第一层了")
    elif choices== 'q':
        exit("程序结束")
    else:
        continue

3.只回退一层

只能回到上一层
# current_layer=memu
# last_layer=memu
# while True:
#     for  k  in current_layer:
#         print(k)
#     choices=input("请输入>>>>").strip()
#     if choices in current_layer: #memu[湖南]
#         last_layer=current_layer   #在进入下一层之前前层，保存当前层
#         current_layer=current_layer[choices] #memu[湖南][长沙]
#     elif choices=="b":
#         current_layer=last_layer
#     elif choices=="q":
#         exit("程序退出")
#     else:
#         continue