Advent of Code Leaderboard 2025 / Day 4

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Leaderboard

	Name	Language	Tokens Sum	Tokens Part 1	Tokens Part 2	Last change
1	Frederik Bonfanti	Ruby	178	83	95	2 days ago
2	Vadzim Kapichenka	Kotlin	236	97	139	18 hours ago
3	progheal	C++	276	127	149	2 days ago
4	Abbas Moosajee	Python	317	148	169	2 days ago
5	Valentin Slawicek	Kotlin	386	172	214	3 days ago
6	Akke	C	417	188	229	2 days ago

Rules

You're welcome to participate alone or in a team.
You may submit multiple solutions and explore different programming languages.
Stick to the standard library of your language, no further dependencies/libraries, except the ones which OneCompiler provides (e.g. NumPy for Python).
Ensure your code aligns to the template (Python, Rust, Go, Kotlin, JavaScript, C#, TypeScript, C++, Java, C, Swift, Scala, Ruby, Bash), reading the puzzle input from stdin (terminated with end-of-file), and printing the solution to stdout.
Please refrain from making network requests, reading data from files, or storing data in variable/function/class names for reflection.
Your code must be able to process all valid Advent of Code inputs. Golfcoder might reevaluate correctness of your solution with different inputs after your submission.

214 tokens in Kotlin for part 2 by Valentin Slawicek

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funmain(){
valchars=generateSequence(::readLine).toMutableList().map{it.toMutableList()}
fungetChar(x:Int,y:Int)=chars.getOrNull(x)?.getOrNull(y)

varcount=0
varprevCount=-1
while(count!=prevCount){
prevCount=count
chars.forEachIndexed{x,row->
row.forEachIndexed{y,char->
if(char=='@'&&listOfNotNull(
getChar(x-1,y-1),
getChar(x-1,y),
getChar(x-1,y+1),
getChar(x,y-1),
getChar(x,y+1),
getChar(x+1,y-1),
getChar(x+1,y),
getChar(x+1,y+1),
).count{it=='@'}<4
){
count++
chars.getOrNull(x)?.set(y,' ')
}
}
}
}
println(count)
}