A Solution to durably store your counts. For example number of likes/dislikes on a post.<p>Its time complexity is O(1).<p>Single header only C++ file for storing and retrieving numbers.<p>It does this without increasing the file size, as its not append only DB. Which also means it can be slower on simultaneous writes to an index. Well if your task is just to store likes/dislikes counts, than it must not be much of a problem. As reads are done more than writes for such cases.