Re: Bitcoin puzzle transaction ~32 BTC prize to who solves it
This trick might be very useful for improving a vanity search with a long prefix, without looking for a full match. You skipped a lot of ranges to land on this hash, right? 
You can implement hash comparison logic using unordered_map for fast lookups. Instead of comparing the entire 20-byte HASH160, you can compare only the first 8 bytes with unordered_map.
I meant something else: let's say we want a match on the first 58 bits of the hash.
This means checking 2**58 hashes, on average.
But instead of scanning linearly one key after the next, jump around according to mcdouglasx/bibilgin strategies (trade off precision with probabilities).
That's why I said it can be a good improvement to find vanity addresses faster, but since there are skipped ranges, other matching prefixes might get lost, there is no violation. But this is not something that a vanity search would ever care about. Only something that should worry someone who wants to solve a puzzle in an efficient matter (e.g. an exact match).