像列表一样订购但是通过密钥访问？

I used list to place cities into a trip. Then I iterate over the list to display the trip itinerary. I would like to access the cities by the name rather than by the trip order. So, I thought I could use a map rather than a list but the key determines the order. I would still like to control the order of the sequence but be able to access the entries by a key.I used list to place cities into a trip. Then I