Day 1: Trebuchet?!

README.md

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 Development occurs in language-specific directories:
 
-|[Haskell](hs) ![Haskell CI](https://github.com/ephemient/aoc2023/workflows/Haskell%20CI/badge.svg)|
-|--:|
-|[Day1.hs](hs/src/Day1.hs)|
+|[Haskell](hs) ![Haskell CI](https://github.com/ephemient/aoc2023/workflows/Haskell%20CI/badge.svg)|[Kotlin](kt)|
+|--:|--:|
+|[Day1.hs](hs/src/Day1.hs)|[Day1.kt](kt/aoc2023-lib/src/commonMain/kotlin/com/github/ephemient/aoc2023/Day1.kt)|

kt/.gitignore

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+.gradle/
+.idea/
+build/
+local.properties
+*~

kt/README.md

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+# [Advent of Code 2023](https://adventofcode.com/2023)
+### my answers in [Kotlin](https://www.kotlinlang.org/)
+
+This project builds with [Gradle](https://gradle.org/).
+
+Run the test suite:
+
+```sh
+./gradlew :aoc2023-lib:allTests
+```
+
+Run [kotlinx.benchmark](https://github.com/Kotlin/kotlinx-benchmark) ([JMH](https://openjdk.java.net/projects/code-tools/jmh/)) benchmarks:
+
+```sh
+./gradlew :aoc2023-exe:benchmark
+```
+
+Print solutions for the inputs provided in local data files:
+
+```sh
+./gradlew :aoc2023-exe:jvmRun :aoc2023-exe:run{Debug,Release}Executable{LinuxX64,Macos{X64,Arm64},MingwX64}
+```
+
+Run all checks, including [Detekt](https://detekt.github.io/) static code analysis and [ktlint](https://ktlint.github.io/) formatter:
+
+```sh
+./gradlew check
+```
+
+Check for newer versions of dependencies:
+
+```sh
+./gradlew :dependencyUpdates
+```

kt/aoc2023-exe/build.gradle.kts

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+import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinNativeTarget
+import org.jetbrains.kotlin.gradle.targets.jvm.KotlinJvmTarget
+
+plugins {
+    application
+    kotlin("multiplatform")
+    kotlin("plugin.allopen")
+    alias(libs.plugins.kotlinx.benchmark)
+    id("com.github.ephemient.aoc2023.detekt")
+    id("com.github.ephemient.aoc2023.kotlin.multiplatform.jvm.platform")
+    id("com.github.ephemient.aoc2023.kotlin.multiplatform.native.platforms")
+}
+
+application {
+    mainClass = "com.github.ephemient.aoc2023.exe.Main"
+}
+
+kotlin {
+    jvm {
+        withJava()
+    }
+
+    targets.withType<KotlinJvmTarget> {
+        mainRun {
+            mainClass = application.mainClass
+        }
+    }
+
+    targets.withType<KotlinNativeTarget> {
+        binaries.executable {
+            entryPoint = "com.github.ephemient.aoc2023.exe.main"
+        }
+    }
+
+    sourceSets {
+        commonMain {
+            dependencies {
+                implementation(projects.aoc2023Lib)
+                implementation(libs.kotlinx.coroutines)
+            }
+        }
+
+        commonTest {
+            dependencies {
+                implementation(libs.kotlinx.benchmark)
+            }
+        }
+
+        nativeMain {
+            dependencies {
+                implementation(libs.okio)
+            }
+        }
+    }
+}
+
+allOpen {
+    annotation("org.openjdk.jmh.annotations.State")
+}
+
+benchmark {
+    targets {
+        register("jvmTest")
+    }
+}

kt/aoc2023-exe/src/commonMain/kotlin/com/github/ephemient/aoc2023/exe/CommonMain.kt

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+package com.github.ephemient.aoc2023.exe
+
+import com.github.ephemient.aoc2023.days
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+
+internal suspend fun mainImpl(vararg args: String): Unit = withContext(Dispatchers.Default) {
+    for (day in days) {
+        if (args.isNotEmpty() && day.name !in args) continue
+        println("Day ${day.name}")
+        for (part in day.solver(getDayInput(day.day))) println(part())
+        println()
+    }
+}

kt/aoc2023-exe/src/commonMain/kotlin/com/github/ephemient/aoc2023/exe/IO.kt

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+package com.github.ephemient.aoc2023.exe
+
+internal expect suspend fun getDayInput(day: Int): String

kt/aoc2023-exe/src/commonTest/kotlin/com/github/ephemient/aoc2023/exe/Day1Bench.kt

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+package com.github.ephemient.aoc2023.exe
+
+import com.github.ephemient.aoc2023.Day1
+import kotlinx.benchmark.Benchmark
+import kotlinx.benchmark.Scope
+import kotlinx.benchmark.Setup
+import kotlinx.benchmark.State
+import kotlinx.coroutines.runBlocking
+
+@State(Scope.Benchmark)
+class Day1Bench {
+    private lateinit var input: String
+
+    @Setup
+    fun setup() {
+        input = runBlocking {
+            getDayInput(1)
+        }
+    }
+
+    @Benchmark
+    fun part1() = Day1(input).part1()
+
+    @Benchmark
+    fun part2() = Day1(input).part2()
+}

kt/aoc2023-exe/src/jvmMain/kotlin/com/github/ephemient/aoc2023/exe/IO.kt

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+package com.github.ephemient.aoc2023.exe
+
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import java.io.File
+
+@Suppress("InjectDispatcher")
+internal actual suspend fun getDayInput(day: Int): String = withContext(Dispatchers.IO) {
+    File(System.getenv("AOC2023_DATADIR")?.ifEmpty { null } ?: ".", "day$day.txt").readText()
+}

kt/aoc2023-exe/src/jvmMain/kotlin/com/github/ephemient/aoc2023/exe/JvmMain.kt

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+@file:JvmName("Main")
+
+package com.github.ephemient.aoc2023.exe
+
+suspend fun main(vararg args: String): Unit = mainImpl(*args)

kt/aoc2023-exe/src/nativeMain/kotlin/com/github/ephemient/aoc2023/exe/IO.kt

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+package com.github.ephemient.aoc2023.exe
+
+import kotlinx.cinterop.ExperimentalForeignApi
+import kotlinx.cinterop.toKString
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.IO
+import kotlinx.coroutines.withContext
+import okio.Path.Companion.toPath
+import okio.buffer
+import platform.posix.getenv
+
+@OptIn(ExperimentalForeignApi::class)
+internal actual suspend fun getDayInput(day: Int): String = withContext(Dispatchers.IO) {
+    val dataDir = (getenv("AOC2023_DATADIR")?.toKString()?.ifEmpty { null } ?: ".").toPath()
+    okio.FileSystem.SYSTEM.source(dataDir / "day$day.txt").buffer().readUtf8()
+}

kt/aoc2023-exe/src/nativeMain/kotlin/com/github/ephemient/aoc2023/exe/NativeMain.kt

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+package com.github.ephemient.aoc2023.exe
+
+import kotlinx.coroutines.runBlocking
+
+fun main(vararg args: String): Unit = runBlocking {
+    mainImpl(*args)
+}

kt/aoc2023-lib/build.gradle.kts

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+plugins {
+    kotlin("multiplatform")
+    id("com.github.ephemient.aoc2023.detekt")
+    id("com.github.ephemient.aoc2023.kotlin.multiplatform.jvm.platform")
+    id("com.github.ephemient.aoc2023.kotlin.multiplatform.native.platforms")
+}
+
+kotlin {
+    sourceSets {
+        commonTest {
+            dependencies {
+                implementation(kotlin("test"))
+                implementation(libs.kotlinx.coroutines.test)
+            }
+        }
+
+        jvmTest {
+            dependencies {
+                implementation(kotlin("test-junit5"))
+                implementation(libs.junit.jupiter.api)
+                runtimeOnly(libs.junit.jupiter.engine)
+            }
+        }
+    }
+}
+
+tasks.jvmTest {
+    useJUnitPlatform()
+}

kt/aoc2023-lib/src/commonMain/kotlin/com/github/ephemient/aoc2023/Day1.kt

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+package com.github.ephemient.aoc2023
+
+class Day1(input: String) {
+    private val lines = input.lines()
+
+    fun part1() = solve(digits)
+
+    fun part2() = solve(extendedDigits)
+
+    private fun solve(values: Collection<IndexedValue<String>>): Int = lines.sumOf { line ->
+        val subset = values.filter { it.value in line }
+        if (subset.isNotEmpty()) {
+            10 * subset.minBy { line.indexOf(it.value) }.index + subset.maxBy { line.lastIndexOf(it.value) }.index
+        } else {
+            0
+        }
+    }
+
+    companion object {
+        private val digits = List(10) { IndexedValue(it, it.toString()) }
+        private val extendedDigits = digits + listOf(
+            IndexedValue(1, "one"),
+            IndexedValue(2, "two"),
+            IndexedValue(3, "three"),
+            IndexedValue(4, "four"),
+            IndexedValue(5, "five"),
+            IndexedValue(6, "six"),
+            IndexedValue(7, "seven"),
+            IndexedValue(8, "eight"),
+            IndexedValue(9, "nine"),
+        )
+    }
+}

kt/aoc2023-lib/src/commonMain/kotlin/com/github/ephemient/aoc2023/Days.kt

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+package com.github.ephemient.aoc2023
+
+val days = listOf(
+    Day(1) { with(Day1(it)) { listOf({ part1() }, { part2() }) } },
+)
+
+data class Day(
+    val day: Int,
+    val name: String = day.toString(),
+    val solver: (String) -> List<suspend () -> Any?>,
+)

kt/aoc2023-lib/src/commonTest/kotlin/com/github/ephemient/aoc2023/Day1Test.kt

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+package com.github.ephemient.aoc2023
+
+import kotlinx.coroutines.test.runTest
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class Day1Test {
+    @Test
+    fun part1() = runTest {
+        assertEquals(142, Day1(example1).part1())
+    }
+
+    @Test
+    fun part2() = runTest {
+        assertEquals(281, Day1(example2).part2())
+    }
+
+    companion object {
+        private val example1 =
+            """
+            |1abc2
+            |pqr3stu8vwx
+            |a1b2c3d4e5f
+            |treb7uchet
+            |""".trimMargin()
+
+        private val example2 =
+            """
+            |two1nine
+            |eightwothree
+            |abcone2threexyz
+            |xtwone3four
+            |4nineeightseven2
+            |zoneight234
+            |7pqrstsixteen
+            |""".trimMargin()
+    }
+}

kt/build.gradle.kts

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+plugins {
+    alias(libs.plugins.kotlin.plugin.allopen) apply false
+    alias(libs.plugins.kotlinx.benchmark) apply false
+    alias(libs.plugins.dependency.updates)
+    id("com.github.ephemient.aoc2023.detekt")
+}
+
+tasks.detekt {
+    setSource(files().apply { from(layout.projectDirectory.asFileTree.matching { include("*.kts") }) })
+}
+
+tasks.dependencyUpdates {
+    revision = "release"
+    gradleReleaseChannel = "current"
+}

kt/buildSrc/build.gradle.kts

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+plugins {
+    `kotlin-dsl`
+}
+
+group = "com.github.ephemient.aoc2023.build-logic"
+
+gradlePlugin {
+    plugins {
+        create("KotlinMultiplatformDefaultHierarchyPlugin") {
+            id = "com.github.ephemient.aoc2023.kotlin.multiplatform.base"
+            implementationClass = "com.github.ephemient.aoc2023.buildsrc.KotlinMultiplatformBasePlugin"
+        }
+        create("KotlinMultiplatformJvmPlatformPlugin") {
+            id = "com.github.ephemient.aoc2023.kotlin.multiplatform.jvm.platform"
+            implementationClass = "com.github.ephemient.aoc2023.buildsrc.KotlinMultiplatformJvmPlatformPlugin"
+        }
+        create("KotlinMultiplatformNativePlatformsPlugin") {
+            id = "com.github.ephemient.aoc2023.kotlin.multiplatform.native.platforms"
+            implementationClass = "com.github.ephemient.aoc2023.buildsrc.KotlinMultiplatformNativePlatformsPlugin"
+        }
+    }
+}
+
+dependencies {
+    implementation(kotlin("gradle-plugin", libs.versions.kotlin.get()))
+    implementation(libs.detekt.plugin)
+}

kt/buildSrc/settings.gradle.kts

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+pluginManagement {
+    repositories {
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}
+
+dependencyResolutionManagement {
+    repositories {
+        mavenCentral()
+    }
+
+    versionCatalogs {
+        create("libs") {
+            from(files("../gradle/libs.versions.toml"))
+        }
+    }
+}
+
+rootProject.name = "buildSrc"