This is quite nice There are many flavours of bitsets. Sometimes it's not the largest element that's a limit but the cardinality. You should also take note of

This is quite nice There are many flavours of bitsets. Sometimes it's not the largest element that's a limit but the cardinality. You should also take note of the cost of clearing a bitset: This cost is almost never included in performance considerations. For instance, when you're making small random subsets (of size k) of a set (size n) you might be tempted to use a bitset and recycle it between subsets. you typically end up with a performance of k.O(1) for set but O(n) for a clear. pick your poison ;)