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.
Code:
std::unordered_map<std::string, int> baby_table;
char key_buffer[9];
int index;
while (fread(key_buffer, 8, 1, pipe) == 1) {
key_buffer[8] = '\0';
fread(&index, sizeof(index), 1, pipe);
baby_table[key_buffer] = index;
}
char key_buffer[9];
int index;
while (fread(key_buffer, 8, 1, pipe) == 1) {
key_buffer[8] = '\0';
fread(&index, sizeof(index), 1, pipe);
baby_table[key_buffer] = index;
}
Here is a link for reference:
https://bitcointalk.org/index.php?topic=5509916.msg65097786#msg65097786
This approach is incredibly fast but consumes a large amount of RAM, especially when the number of unique 8-byte prefixes is high. Every optimization has trade-offs—while something is gained, something else is lost.
The bigger challenge lies in optimizing SECP256K1 itself.