solve 23rd day 1st task

0legg · 0legg · commit d0d8dd624107 · 2024-12-22T21:11:11.000-08:00
diff --git a/year2024/src/main/kotlin/net/olegg/aoc/year2024/day23/Day23.kt b/year2024/src/main/kotlin/net/olegg/aoc/year2024/day23/Day23.kt
@@ -0,0 +1,34 @@
+package net.olegg.aoc.year2024.day23
+
+import net.olegg.aoc.someday.SomeDay
+import net.olegg.aoc.utils.parseInts
+import net.olegg.aoc.utils.toPair
+import net.olegg.aoc.utils.transpose
+import net.olegg.aoc.year2024.DayOf2024
+import kotlin.math.absoluteValue
+
+/**
+ * See [Year 2024, Day 23](https://adventofcode.com/2024/day/23)
+ */
+object Day23 : DayOf2024(23) {
+  override fun first(): Any? {
+    val connections = lines.map { it.split("-").sorted() }
+
+    return connections.flatMapIndexed { i, connI ->
+      connections.drop(i + 1).flatMapIndexed { j, connJ ->
+        val subset = (connI + connJ).toSet()
+        if (subset.size == 3) {
+          connections.drop(i + 1 + j + 1).mapNotNull { connK ->
+            (subset + connK).toSet().takeIf { it.size == 3 }
+          }
+        } else {
+          emptyList()
+        }
+      }
+    }.count { set ->
+      set.any { it.startsWith("t") }
+    }
+  }
+}
+
+fun main() = SomeDay.mainify(Day23)
