Solved day11 part 1

Author: Gentleman1983

day11/src/main/kotlin/de/havox_design/aoc2023/day11/Day11.kt

@@ -1,12 +1,76 @@
 package de.havox_design.aoc2023.day11
 
+import kotlin.math.abs
+
 class Day11(private var filename: String) {
+    private val ICON_GALAXY = "#"
+
     fun solvePart1(): Long =
-        374L
+        processSumOfAllDistances(getResourceAsText(filename))
 
     fun solvePart2(): Long =
         0L
 
+    private fun processSumOfAllDistances(input: List<String>): Long {
+        val galaxies = input
+            .flatMapIndexed { y, s ->
+                s.mapIndexed { x, c -> if (c == ICON_GALAXY.first()) Pair(y.toLong(), x.toLong()) else null }
+            }
+            .filterNotNull()
+        val emptyRows = input
+            .withIndex()
+            .filter { !it.value.contains(ICON_GALAXY) }
+            .map { it.index.toLong() }
+        val emptyColumns = input
+            .map { it.toList() }
+            .transpose()
+            .withIndex()
+            .filter {
+                !it
+                    .value
+                    .joinToString("") { c -> c.toString() }
+                    .contains(ICON_GALAXY)
+            }
+            .map { it.index.toLong() }
+        val expandedGalaxies = calculateUniverseExpansion(galaxies, emptyRows, emptyColumns)
+        val galaxyPairs = expandedGalaxies
+            .flatMapIndexed { index, galaxy ->
+                expandedGalaxies
+                    .drop(index + 1)
+                    .map { Pair(galaxy, it) }
+            }
+        val distances = galaxyPairs
+            .map { calculateDistance(it.first, it.second) }
+
+        return distances.sumOf { it }
+    }
+
+    private fun calculateUniverseExpansion(
+        galaxies: List<Pair<Long, Long>>,
+        emptyRows: List<Long>,
+        emptyColumns: List<Long>
+    ) =
+        galaxies
+            .map {
+                Pair(it.first + emptyRows.count { r -> r < it.first },
+                    it.second + emptyColumns.count { c -> c < it.second })
+            }
+
+    private fun calculateDistance(galaxy1: Pair<Long, Long>, galaxy2: Pair<Long, Long>): Long {
+        return abs(galaxy2.first - galaxy1.first) + abs(galaxy2.second - galaxy1.second)
+    }
+
+    private fun <T> List<List<T>>.transpose(): List<List<T>> {
+        return when {
+            this.isEmpty() -> this
+            else -> (this[0].indices)
+                .map { i ->
+                    (this.indices)
+                        .map { j -> this[j][i] }
+                }
+        }
+    }
+
     private fun getResourceAsText(path: String): List<String> =
         this.javaClass.classLoader.getResourceAsStream(path)!!.bufferedReader().readLines()
 }