Awhile back I encountered a simple programming puzzle to determine whether a string was a pangram, or a perfect pangram. (Although it's worth noting that this particular challenge gave a different meaning than the standard definition of a "perfect pangram," to mean any sentence where every letter appears n times for some positive n). And it was a fun challenge. But recently it got me wondering whether it would be possible to solve this challenge purely with regular expressions. If it is, I expect it will be a pretty gnarly regex. But I'm not even sure it is possible.
Still, if anyone is able to do it, it would be the folks here at Code Golf. So here's the challenge:
Write a regular expression which can determine whether or not a given string is a pangram. You can assume that all non-alpha characters have already been stripped out (or don't, if you really want to challenge yourself), and that everything has been transformed into lowercase.
Bonus challenge: write another regular expression to determine whether the given string is a "perfect pangram" by the definition given above.
Examples of an ordinary pangram:
Example of perfect pangrams:
I'm not really sure if this is even possible just with regex alone. If you find that it is, kudos!