Day 11 Part 1

2024/src/main/kotlin/day11.kt

@@ -0,0 +1,31 @@
+fun main() {
+    val input = readInputString("day11.txt").split(" ").map { it.toLong() }
+
+    val part1 = (1..25).fold(input) { result, _ ->
+        result.blink()
+    }.count()
+
+    println("Part 1: $part1")
+
+
+    val part2 = (1..75).fold(input) { result, _ ->
+        result.blink()
+    }.count()
+
+    println("Part 2: $part2")
+
+}
+
+fun List<Long>.blink() = flatMap {
+    val str = "$it"
+    val strLen = str.count()
+
+    when {
+        it == 0L -> listOf(1L)
+        strLen % 2 == 0 -> listOf(
+            str.substring(0, strLen / 2).toLong(),
+            str.substring(strLen / 2).toLong()
+        )
+        else -> listOf(it * 2024)
+    }
+}

2024/src/main/resources/day11.txt

@@ -0,0 +1 @@
+3 386358 86195 85 1267 3752457 0 741