Finished 2024 day 9 both parts

2024/kotlin/src/main/kotlin/Main.kt

@@ -1,6 +1,14 @@
 package com.tymscar
 
+import com.tymscar.day01.solve as day01
+import com.tymscar.day02.solve as day02
+import com.tymscar.day03.solve as day03
+import com.tymscar.day04.solve as day04
+import com.tymscar.day05.solve as day05
+import com.tymscar.day06.solve as day06
+import com.tymscar.day07.solve as day07
 import com.tymscar.day08.solve as day08
+import com.tymscar.day09.solve as day09
 
 fun main() {
     day01()
@@ -11,4 +19,5 @@ fun main() {
     day06()
     day07()
     day08()
+    day09()
 }

2024/kotlin/src/main/kotlin/com/tymscar/day09/part1/part1.kt

@@ -1,5 +1,36 @@
 package com.tymscar.day09.part1
 
+private sealed class Block {
+    data class File(val id: Long) : Block()
+    class Space : Block()
+}
+
 fun solve(input: String): String {
-    return input
+    val memory = input
+        .withIndex()
+        .fold((0L to listOf<Block>())) { (currId, currList), value ->
+            when (value.index % 2) {
+                0 -> (currId + 1 to (currList + List(value.value.digitToInt()) { Block.File(currId) }))
+                else -> (currId to (currList + List(value.value.digitToInt()) { Block.Space() }))
+            }
+        }.second
+
+    val fragmented = memory
+        .fold((0 to memory.count() - 1) to listOf<Block.File>()) { (indices, currList), value ->
+            var (indexLeft, indexRight) = indices
+            while (memory[indexRight] is Block.Space) indexRight--
+            if (indexLeft > indexRight) {
+                return@fold (indices to currList)
+            }
+
+            when (value) {
+                is Block.File -> ((indexLeft + 1 to indexRight) to (currList + memory[indexLeft] as Block.File))
+                is Block.Space -> ((indexLeft + 1 to indexRight - 1) to (currList + memory[indexRight] as Block.File))
+            }
+        }.second
+
+    return fragmented
+        .withIndex()
+        .sumOf { it.value.id * it.index }
+        .toString()
 }

2024/kotlin/src/main/kotlin/com/tymscar/day09/part2/part2.kt

@@ -1,5 +1,60 @@
 package com.tymscar.day09.part2
 
+private sealed class Block {
+    data class File(val id: Long) : Block()
+    class Space : Block()
+}
+
+private data class Chunk(val content: Block, val length: Int)
+
 fun solve(input: String): String {
-    return input
+    val memory = input
+        .withIndex()
+        .fold((0L to listOf<Chunk>())) { (currId, currList), value ->
+            when (value.index % 2) {
+                0 -> (currId + 1 to (currList + Chunk(Block.File(currId), value.value.digitToInt())))
+                else -> (currId to (currList + Chunk(Block.Space(), value.value.digitToInt())))
+            }
+        }.second.toMutableList()
+
+    val chunksIdsToMove = memory
+        .mapNotNull {
+            when (it.content) {
+                is Block.File -> it.content.id
+                is Block.Space -> null
+            }
+        }.reversed()
+
+    chunksIdsToMove.forEach { chunkId ->
+        val chunk = memory.last { it.content is Block.File && (it.content).id == chunkId }
+        val chunkIndex = memory.indexOf(chunk)
+
+        val emptyChunk = memory.firstOrNull() { it.content is Block.Space && it.length >= chunk.length }
+        if (emptyChunk == null) return@forEach
+        val emptyChunkIndex = memory.indexOf(emptyChunk)
+
+        if (emptyChunkIndex >= chunkIndex) return@forEach
+        when {
+            chunk.length == emptyChunk.length -> {
+                memory[emptyChunkIndex] = chunk
+                memory[chunkIndex] = emptyChunk
+            }
+
+            chunk.length < emptyChunk.length -> {
+                memory[emptyChunkIndex] = Chunk(Block.File(chunkId), chunk.length)
+                memory[chunkIndex] = Chunk(Block.Space(), chunk.length)
+                memory.add(emptyChunkIndex + 1, Chunk(Block.Space(), emptyChunk.length - chunk.length))
+            }
+        }
+    }
+
+    return memory
+        .flatMap { List(it.length) { _ -> it.content } }
+        .withIndex()
+        .sumOf {
+            when (it.value) {
+                is Block.File -> (it.value as Block.File).id * it.index
+                is Block.Space -> 0
+            }
+        }.toString()
 }