I picked go for my language this year, which doesn't have good support for sets. May end up writing my own buggy implementation of this.
Most years I choose a language I've never worked with commercially (e.g. Fennel in 2022) and rather than reach for prebuilt libs for timesaving fancy array or set or string ops, I'll invent those wheels myself without dependencies and I find a ton of satisfaction in it. Unwise commercially but ideal for learning and play. And, yeah, bugs!
IMO, when it's not a customer paying for my learning curve, there's a lot to be said for rewalking old paths with new boots (or no boots and funky coloured glasses). Also, a terrible way to get onto the leaderboard IME!
Requires thinking if you want to implement set difference or intersection. I just figured depending on needs using existing built-in types may be fun.
For the problem we don't care how many instances of each letter occurs. We just need to know if there is 0 or 1 instance of a given letter. A set is a pretty good way to do this. Store a set of each "compartment", intersect the two sets, and you should have one value.
We can do the same thing except instead of a set we use an integer and set bits. a-z are bits 0-26 and A_Z are bits 27-52. We can set a bit with bitwise-or. We can intersect two masks with bitwise-and.
My code is probably a little too verbose. I'm not super familiar with python so I wasn't sure the best way to deal with characters and integers. But it's functional.
for key, _ := range first {
if _, found2 := second[key]; found2 {
if _, found3 := third[key]; found3 {
// This is the intersection of 3 sets
}
}
}