需求
    省縣市三級聯動
    用戶輸入河北，則打印河北省下的市，用戶輸入市，則顯示該河北省的這個市下的縣

測試信息
dic = {
    "河北":{
        "石家莊":["鹿泉","槁城","元氏"],
        "邯鄲":["永年","涉縣","磁縣"]
    },
    "河南":{
        "周口":["太康","商水","淮陽"],
        "鄭州":["金水","二七","管城"]
    },
    "山西":{
        "太原":["迎澤","清徐","陽曲"],
        "大同":["陽高","天鎮","靈丘"]
    }
}

dic = {
    "河北":{
        "石家莊":["鹿泉","槁城","元氏"],
        "邯鄲":["永年","涉縣","磁縣"]
    },
    "河南":{
        "周口":["太康","商水","淮陽"],
        "鄭州":["金水","二七","管城"]
    },
    "山西":{
        "太原":["迎澤","清徐","陽曲"],
        "大同":["陽高","天鎮","靈丘"]
    }
}
while True:
    print(‘請在以下省份中選擇：‘)
    for i in dic.keys():
        print(i)
    pro=input(‘輸入你要查詢的省份(退出請按q)：‘).strip().lower()
    if pro == ‘q‘:
        print(‘再見！‘)
        exit()
    if pro not in dic.keys():
        print(‘要查詢的省份不存在或者你的輸入有誤，請重新輸入‘)
        continue
    else:
        tag=True
        while tag:
            print(‘%s有以下城市：‘ % pro)
            for c in dic[pro].keys():
                print(c)
            city=input(‘請輸入你要查詢的城市（回到省份查找請按p，退出請按q）：‘).strip().lower()
            if city == ‘q‘:
                print(‘再見!‘)
                exit()
            if city == ‘p‘:
                break
            if city not in dic[pro].keys():
                print(‘要查詢的城市不存在或者你的輸入有誤，請重新輸入‘)
                continue
            else:
                while tag:
                    print(‘%s有以下縣區‘ % city)
                    for cou in dic[pro][city]:
                        print(cou)
                    county=input(‘重新選擇省份請按p，重新選擇城市請按c，退出請按q：‘).strip().lower()
                    if county == ‘q‘:
                        print(‘再見！‘)
                        exit()
                    if county == ‘c‘:
                        break
                    if county == ‘p‘:
                        tag=False
                        break
                    else:
                        print(‘輸入錯誤，請重新輸入‘)
                        continue

本文出自 “lyndon” 博客，請務必保留此出處http://lyndon.blog.51cto.com/11474010/1947436

省縣市三級聯動