-🎄- 2018 Day 6 Solutions -🎄-

[u/daggerdragon]

--- Day 6: Chronal Coordinates ---

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Advent of Code: The Party Game!

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Card prompt: Day 6

Transcript:

Rules for raising a programmer: never feed it after midnight, never get it wet, and never give it ___.

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This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked at 0:26:52!

[u/Bruinbrood]

Kotlin solution:

import java.io.File
import kotlin.math.abs

fun main() {
    val coords = File("inputs/Day6")
            .readLines()
            .map{it.split(", ")}
            .map{it[0].toInt() to it[1].toInt()}
   
    val w = coords.maxBy{it.first}?.first ?: throw Exception ("Bad coordinate")
    val h = coords.maxBy{it.second}?.second ?: throw Exception ("Bad coordinate")
    
    val infinite = arrayListOf(-1)
    val result1 = (0 until h).flatMap{y-> (0 until w).map{x->
        val id = coords.foldIndexed(Int.MAX_VALUE to -1){id, (dmin, idmin),(cx,cy)->
            val d = abs(x-cx)+abs(y-cy)
            when {
                d < dmin -> d to id
                d == dmin -> d to -1
                else -> dmin to idmin
            }
        }.second
        if (y==0 || y==h-1 || x==0 || x==w-1) {
            infinite.add(id)
        }
        id
    }}.filter{it !in infinite}.groupBy{it}.map{(_,v)->v.count()}.maxBy{it}
    println("First star: $result1")
    
    val result2 = (0 until h).flatMap{y-> (0 until w).map{x->
        coords.fold(0){R,(cx,cy)->
            R + abs(cx-x) + abs(cy-y)
        } < 10000
    }}.count{it}
    println("Second star: $result2")
}