How to implement a Least Frequently Used (LFU) cache?

Question

Least Frequently Used (LFU) is a type of cache algorithm used to manage memory within a computer. The standard characteristics of this method involve the system keeping track of

Answer 1

How about a priority queue? You can keep elements sorted there with keys representing the frequency. Just update the object position in the queue after visiting it. You can update just from time to time for optimizing the performance (but reducing precision).