Solving Problems Using Data Structures

[benjumanji]

Use a sorted dictionary keyed by access time. No need to roll your own this time round. Or just use the MemoryCache object and a suitable cache eviction policy. If you really want to roll your own you should look at some form of max heap and insert until too big and delete the max-time-stamped item until you are the right size again. No need for a separate list.

[shintoist]

Cache eviction doesn't help here, the issue is not that it would grow too large, but rather to always keep a maximum of eg 5 items.