2024 Day 1

Author: WVerlaek

.github/workflows/tests.yml

@@ -23,7 +23,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-java@v4
         with:
-          java-version: 11
+          java-version: 17
           distribution: zulu
 
       # Runs a single command using the runners shell

src/main/kotlin/y24/Day1.kt

@@ -0,0 +1,39 @@
+package y24
+
+import common.puzzle.solvePuzzle
+import common.puzzle.Input
+import common.puzzle.Puzzle
+import common.datastructures.*
+import common.ext.*
+import common.puzzle.splitToInts
+import common.util.*
+import java.util.*
+import kotlin.math.*
+import kotlin.system.exitProcess
+
+
+fun main() = solvePuzzle(year = 2024, day = 1) { Day1(it) }
+
+class Day1(val input: Input) : Puzzle {
+    val left = input.lines
+        .map { it.splitToInts(separator = "   ").first() }
+        .sorted()
+    val right = input.lines
+        .map { it.splitToInts(separator = "   ").last() }
+        .sorted()
+
+    override fun solveLevel1(): Any {
+        return left.mapIndexed { index, l ->
+            val r = right[index]
+            abs(l - r)
+        }.sum()
+    }
+
+    override fun solveLevel2(): Any {
+        val rightCounts = right.groupingBy { it }.eachCount()
+        return left.sumOf { l ->
+            val count = rightCounts[l] ?: 0
+            l.toLong() * count
+        }
+    }
+}

src/test/kotlin/y24/Day1Test.kt

@@ -0,0 +1,28 @@
+package y24
+
+import common.puzzle.Input
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+
+internal class Day1Test {
+    private val sample = Input("""
+    3   4
+    4   3
+    2   5
+    1   3
+    3   9
+    3   3
+    """.trimIndent())
+
+    private val day = Day1(sample)
+
+    @Test
+    fun solveLevel1() {
+        assertEquals(11, day.solveLevel1())
+    }
+
+    @Test
+    fun solveLevel2() {
+         assertEquals(31L, day.solveLevel2())
+    }
+}

workflow/new.sh

@@ -4,7 +4,7 @@
 
 set -Eeuo pipefail
 
-CURRENT_YEAR="23"
+CURRENT_YEAR="24"
 
 export DAY="${1:?"Usage: ./new.sh <day> [<year>]"}"
 export YEAR="${2:-"$CURRENT_YEAR"}"
@@ -45,5 +45,5 @@ envsubst < "$SRC_TEMPLATE" > "$SRC_FILE"
 envsubst < "$TEST_TEMPLATE" > "$TEST_FILE"
 
 echo "Opening files"
-gp open "$SRC_FILE"
-gp open "$TEST_FILE"
+gp open "$SRC_FILE" || echo "Failed to open $SRC_FILE"
+gp open "$TEST_FILE" || echo "Failed to open $TEST_FILE"