2. Keeping counts of things as mutable state.

MutableMap<T, Long>

is okay-ish for this, but incrementing feels very awkward

myCounts[something] = myCounts.getOrDefault(something, 0) + numberFound

I've generally found that updating state in maps can be a bit annoying so I do have a general helper function (which I think would be worth having in stdlib tbh)

fun <K, V> MutableMap<K, V>.update(k: K, transform: (V?) -> V) = set(k, transform(get(k)))

So it becomes

myCounts.update(k) { (it ?: 0) + numberFound

But still, end up repeating quite a bit. If there isn't a better way then I may just have a dedicated Counter (a la python) and possibly deal with both things with one stone

Advent of Code 2021 day 15 🧵

Tip: if you're stuck on part 2 (like me) because your code gives the right result for the example input, but wrong for your own input, check that your path finding algorithm of part 1 produces the right result for the following input (in thread)

Advent of Code 2021 day 16 🧵

without looking at the docs, guess what this does:

val packetVersion = stringbuilder.removeRange(0..2).toLong(2)

I guessed wrong this morning 😉

is there a nice alternative for the following?

// s is my input representation and once a portion is processed, I remove that portion

val sub = mutableListOf<Packet>()

while(!s.isEmpty()) {
   sub.add(processPacket(s))
}

return sub

Advent of Code 2021 day 17 🧵

Advent of Code 2021 day 18 🧵

so I have a list that I want to fold but I want the initial element to be the FIRST element of the list. Does kotlin have a specific method for this?

Is there a kotlin method for doing this?

var explosionResult = result.explode(0)
while (explosionResult.explosionOcurred) {
    explosionResult = result.explode(0)
}

Advent of Code 2021 day 19 🧵

any idiomatic way to do this?

functionThatReturnsNullable() ?: doOnNull() followed by continue

my understanding was that you would pick a property for something that is essentially cheap/cached/"read off" and a function for something that actually requires computation. So size as a property makes sense; any collection in Kotlin should cheaply know its size. But if it cheaply knows its size, it must cheaply know whether its empty? If size has to be cheaply available, then even having

isEmpty

as an extension property with

size == 0

seems fine...

Advent of Code 2021 day 20 🧵

Anyone else take scratch notes while puzzle-solving? I have a mini whiteboard I can use on my desk.

Any votes on tonight's difficulty from 1 being day 1-level to 10 being 👿?

Advent of Code 2021 day 21 🧵

Advent of Code 2021 day 22 🧵

Is the description the same for everyone else?

Advent of Code 2021 day 23 🧵

Advent of Code 2021 day 24 🧵

Advent of Code 2021 day 25 🎄

Did anybody here end up winning any prizes from JetBrains for participating in Advent of Code? If so, what did you win? 🙂

Dear all! Thank you so much for your participation in AoC 2021, for your posts, discussions, for sharing your solutions and helping others. It was great! With this blogpost and video we’d like to announce and congratulate the winners 🥁 https://blog.jetbrains.com/kotlin/2022/01/advent-of-code-2021-in-kotlin-winners/

How can I remove duplicated consecutive values in a list by a specific field? [{a,1},{b,1},{c,2},{d,2},{e,1}] -> [{a,1}{c,2},{e,1}]

Did y'all already know about this? https://blog.jetbrains.com/kotlin/2022/02/kotlin-heroes-episode-9/

Advent Advent! :kotlinnew: 💕 Thanks for the fantastic time and the shirts

D-0x20, folks. Exciting!

Are there plans to have another contest this year?