added 2024 part 2

2024/02/Kotlin/src/main/kotlin/Main.kt

@@ -0,0 +1,64 @@
+package ch.makhankov
+
+import kotlin.math.absoluteValue
+import kotlin.math.sign
+
+fun main() {
+    val filenames = listOf("example.txt", "input.txt")
+    filenames.forEach { filename ->
+        val data = readFile(filename)
+        val dataRows = data?.split("\r\n")
+        val dataEntries = dataRows?.map { it.split(" ") }?.map { it.map { s -> s.toInt() } }
+        val result = dataEntries?.let { calculateSafeRecords(it) }
+        val resultDampened = dataEntries?.let { calculateSafeRecordsWithTolerance(it) }
+        println("Part 1: $result")
+        println("Part 2: $resultDampened")
+    }
+}
+
+fun readFile(filename: String): String? {
+    return object {}.javaClass.getResource("/$filename")?.readText()
+}
+
+fun diffFromList(list: List<Int>): List<Int> {
+    return list.dropLast(1).mapIndexed { index, i -> i - list[index + 1] }
+}
+
+fun sameSign(list: List<Int>): Boolean {
+    val temp = list[0]
+    return list.drop(1).all { it.sign == temp.sign }
+}
+
+fun inIncreaseRange(list: List<Int>, range: IntRange): Boolean {
+    return list.all { range.contains(it.absoluteValue) }
+}
+
+fun calculateSafeRecords(input: List<List<Int>>): Int {
+    val checkValidity = input.map { transformation(it) }
+    return checkValidity.count { it }
+}
+
+fun calculateSafeRecordsWithTolerance(input: List<List<Int>>): Int {
+    val checkValidity = input.map { transformation(it) }
+    var count = checkValidity.count { it }
+    checkValidity.forEachIndexed { index, value ->
+        if (!value) {
+            val record = input[index]
+            for ((rIndex, _) in record.withIndex()) {
+                val subList = record.filterIndexed { i, _ -> i != rIndex }
+                if (transformation(subList)) {
+                    count = count.inc()
+                    break
+                }
+            }
+        }
+    }
+    return count
+}
+
+fun transformation(input: List<Int>): Boolean{
+    val diffs = diffFromList(input)
+    val sameSign = sameSign(diffs)
+    val inRange = inIncreaseRange(diffs, 1..3)
+    return sameSign && inRange
+}