2015: day 10 parts 1 & 2

src/main/kotlin/io/plagov/advent/aoc2015/Day10.kt

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+package io.plagov.advent.aoc2015
+
+class Day10 {
+
+  fun partOne(input: String): Int {
+    var result = input
+
+    repeat(40) {
+      result = getNextSequence(result)
+    }
+
+    return result.length
+  }
+
+  fun partTwo(input: String): Int {
+    var result = input
+
+    repeat(50) {
+      result = getNextSequence(result)
+    }
+
+    return result.length
+  }
+
+  private fun getNextSequence(input: String): String {
+    val regex = """(\d)\1*""".toRegex()
+
+    return regex.findAll(input)
+      .map { "${it.value.length}${it.value.first()}" }
+      .joinToString(separator = "") { it }
+  }
+}

src/test/kotlin/io/plagov/advent/aoc2015/Day10Test.kt

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+package io.plagov.advent.aoc2015
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+
+class Day10Test {
+
+  private val day10 = Day10()
+
+  private val input = "1321131112"
+
+  @Test
+  fun solveFirst() {
+    assertEquals(492982, day10.partOne(input))
+  }
+
+  @Test
+  fun solveSecond() {
+    assertEquals(6989950, day10.partTwo(input))
+  }
+}