此种方法省去的重复性的循环语句，用一个循环代替了所有
Menu = {
"北京":{
"昌平":["沙河","辛庄","南口"],
"朝阳":["太阳宫","孙河","管庄"],
"海淀":["上地","西三旗","西二旗"]
},
"河南":{
"郑州":["二七区","中原区","金水区"],
"洛阳":["西工区","老城区","洛龙区"]
},
"河北":{
"石家庄":["新华区","长安区","正定县"],
"邯郸":["丛台区","复兴区","大名县"]
},
"广东":{
"广州":["南沙区","花都区","番禹区"],
"深圳":["龙岗区","罗湖区","盐田区"],
"东莞":["南城区","东城区","万江区"]
},
}
cur_menu = Menu
parrent_menu = []
while True:
for keys in cur_menu:
print(keys)
choice = input("请选择>>>").strip()
if len(choice) == 0:
continue
if choice in cur_menu:
parrent_menu.append(cur_menu)
cur_menu = cur_menu[choice]
elif choice == "b":
if parrent_menu:
cur_menu = parrent_menu.pop()
else:
print("输入错误，请重新输入")
