2024 - Day 23 - part 1&2

src/main/kotlin/no/rodland/advent_2024/Day23.kt

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+package no.rodland.advent_2024
+
+import no.rodland.advent.Day
+
+// template generated: 23/12/2024
+// Fredrik Rødland 2024
+
+class Day23(val input: List<String>) : Day<Int, String, List<Pair<String, String>>> {
+
+    private val parsed = input.parse()
+    private val computers = buildMap<String, MutableSet<String>> {
+        parsed.forEach { (first, second) ->
+            computeIfAbsent(first) { mutableSetOf() }.add(second)
+            computeIfAbsent(second) { mutableSetOf() }.add(first)
+        }
+    }
+
+    override fun partOne(): Int {
+        return groupsOfThree().filter { it.any { c -> c.startsWith("t") } }.size
+    }
+
+    override fun partTwo(): String {
+        return findLargestGroup().sorted().joinToString(",")
+    }
+
+    private fun groupsOfThree(): Set<List<String>> {
+        return computers
+            .mapNotNull { (computer, neighbours) ->
+                val neighboursList = neighbours.toList()
+                neighboursList.indices.mapNotNull { i ->
+                    val restRange = i + 1 until neighboursList.size
+                    restRange.mapNotNull { j ->
+                        val neighbor1 = neighboursList[i]
+                        val neighbor2 = neighboursList[j]
+                        if (computers[neighbor1]?.contains(neighbor2) == true) {
+                            setOf(computer, neighbor1, neighbor2).sorted()
+                        } else {
+                            null
+                        }
+                    }
+                }.flatten()
+            }
+            .flatten()
+            .toSet()
+    }
+
+    private fun findLargestGroup(): Set<String> {
+        return groups().maxBy { it.size }.sorted().toSet()
+    }
+
+    private fun groups(): List<MutableSet<String>> {
+        val visited = mutableSetOf<String>()
+        val groups = computers.keys.mapNotNull { computer ->
+            if (computer !in visited) {
+                val group = mutableSetOf(computer)
+                val neighbors = computers[computer].orEmpty()
+                for (neighbor in neighbors) {
+                    if (group.all { computers[it]?.contains(neighbor) == true }) {
+                        group.add(neighbor)
+                    }
+                }
+                visited.addAll(group)
+                group
+            } else {
+                null
+            }
+        }
+        return groups
+    }
+
+    override fun List<String>.parse(): List<Pair<String, String>> {
+        return map { line ->
+            val (first, second) = line.split("-")
+            first to second
+        }
+    }
+
+    override val day = "23".toInt()
+}

src/test/kotlin/no/rodland/advent_2024/Day23Test.kt

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+package no.rodland.advent_2024
+
+import no.rodland.advent.*
+import org.junit.jupiter.api.Nested
+import org.junit.jupiter.api.Test
+import readFile
+
+//
+//  run: download_aoc_input.sh to download input
+//
+
+@Suppress("ClassName")
+@DisableSlow
+internal class Day23Test {
+    private val data23 = "2024/input_23.txt".readFile()
+    private val test23 = "2024/input_23_test.txt".readFile()
+
+    private val resultTestOne = 7
+    private val resultTestTwo = "co,de,ka,ta"
+    private val resultOne = 1215
+    private val resultTwo = "bm,by,dv,ep,ia,ja,jb,ks,lv,ol,oy,uz,yt"
+
+    val test = defaultTestSuiteParseOnInit(
+        Day23(data23),
+        Day23(test23),
+        resultTestOne,
+        resultOne,
+        resultTestTwo,
+        resultTwo,
+        { Day23(data23) },
+        { Day23(test23) },
+        numTestPart1 = 4,
+        numTestPart2 = 100
+    )
+
+    @Nested
+    inner class Init {
+        @Test
+        fun `23,-,example,1`() {
+            report(AOCTest({ "123".toInt() }, Unit, 123, 5, "23".toInt(), Part.TWO, false, "example"))
+        }
+
+        @Test
+        fun `23,-,example,2`() {
+            report(test.initTest.copy())
+        }
+
+        @Test
+        fun `23,-,test,init`() {
+            report(test.initTest)
+        }
+
+        @Test
+        fun `23,-,live,init`() {
+            report(test.initLive)
+        }
+    }
+
+    @Nested
+    inner class `Part 1` {
+        @Test
+        fun `23,1,test`() {
+            report(test.testPart1)
+        }
+
+        @Test
+        fun `23,1,live,1`() {
+            report(test.livePart1)
+        }
+    }
+
+    @Nested
+    inner class `Part 2` {
+        @Test
+        fun `23,2,test`() {
+            report(test.testPart2)
+        }
+
+        @Test
+        fun `23,2,live,1`() {
+            report(test.livePart2)
+        }
+    }
+}

src/test/resources/2024/input_23_test.txt

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+kh-tc
+qp-kh
+de-cg
+ka-co
+yn-aq
+qp-ub
+cg-tb
+vc-aq
+tb-ka
+wh-tc
+yn-cg
+kh-ub
+ta-co
+de-co
+tc-td
+tb-wq
+wh-td
+ta-ka
+td-qp
+aq-cg
+wq-ub
+ub-vc
+de-ta
+wq-aq
+wq-vc
+wh-yn
+ka-de
+kh-ta
+co-tc
+wh-qp
+tb-vc
+td-yn