2025, Day 5

Author: edgars-supe

.idea/runConfigurations/2025__Day_5.xml

@@ -0,0 +1,25 @@
+package lv.esupe.aoc.utils
+
+infix fun IntRange.overlaps(other: IntRange): Boolean {
+    return this.first <= other.last && other.first <= this.last
+}
+
+infix fun LongRange.overlaps(other: LongRange): Boolean {
+    return this.first <= other.last && other.first <= this.last
+}
+
+fun IntRange.mergeWith(other: IntRange): IntRange {
+    if (!(this overlaps other)) {
+        throw IllegalArgumentException("Ranges must overlap to be merged")
+    }
+
+    return minOf(this.first, other.first)..maxOf(this.last, other.last)
+}
+
+fun LongRange.mergeWith(other: LongRange): LongRange {
+    if (!(this overlaps other)) {
+        throw IllegalArgumentException("Ranges must overlap to be merged")
+    }
+
+    return minOf(this.first, other.first)..maxOf(this.last, other.last)
+}

src/main/kotlin/lv/esupe/aoc/utils/Range.kt

@@ -0,0 +1,48 @@
+package lv.esupe.aoc.year2025
+
+import lv.esupe.aoc.Puzzle
+import lv.esupe.aoc.solve
+import lv.esupe.aoc.utils.chunkedBy
+import lv.esupe.aoc.utils.mergeWith
+import lv.esupe.aoc.utils.overlaps
+
+fun main() = solve { Day5() }
+
+class Day5 : Puzzle<Int, Long>(2025, 5) {
+    override val input = rawInput
+
+    private val ranges: List<LongRange>
+    private val ids: List<Long>
+
+    init {
+        val (ranges, ids) = input.chunkedBy { it.isBlank() }
+        this.ranges = ranges
+            .map { line ->
+                val (a, b) = line.split("-")
+                    .map { it.toLong() }
+                a..b
+            }
+            .sortedBy { it.first }
+        this.ids = ids.map { it.toLong() }
+    }
+
+    override fun solvePartOne(): Int {
+        return ids.count { id -> ranges.any { range -> id in range } }
+    }
+
+    override fun solvePartTwo(): Long {
+        val queue = ranges.toMutableList()
+        val condensed = mutableListOf<LongRange>()
+        while (queue.isNotEmpty()) {
+            val rangeA = queue.removeAt(0)
+            val rangeB = queue.firstOrNull { rangeB -> rangeA overlaps rangeB }
+            if (rangeB != null) {
+                queue.remove(rangeB)
+                queue.add(rangeA.mergeWith(rangeB))
+            } else {
+                condensed.add(rangeA)
+            }
+        }
+        return condensed.sumOf { range -> range.last - range.first + 1 }
+    }
+}

src/main/kotlin/lv/esupe/aoc/year2025/Day5.kt

@@ -0,0 +1,42 @@
+package lv.esupe.aoc.utils
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Nested
+import org.junit.jupiter.api.Test
+
+class RangeTest {
+
+    @Nested
+    inner class Overlaps {
+
+        @Test
+        fun `overlaps functions correctly`() {
+            assertTrue(1..10 overlaps 5..15)
+            assertTrue(1..10 overlaps 5..10)
+            assertTrue(1..10 overlaps 10..20)
+            assertTrue(1..10 overlaps 1..10)
+            assertTrue(1..10 overlaps (1 until 10))
+            assertTrue(1..10 overlaps (2 until 10))
+            assertTrue(1..10 overlaps -10..1)
+            assertTrue(1..10 overlaps -10..5)
+
+            assertFalse(1..10 overlaps -10..0)
+            assertFalse(1..10 overlaps (-10 until 1))
+            assertFalse(1..10 overlaps 11..20)
+        }
+    }
+
+    @Nested
+    inner class MergeWith {
+
+        @Test
+        fun `mergeWith functions correctly`() {
+            assertEquals(1..10, (1..5).mergeWith(5..10))
+            assertEquals(1..10, (1..10).mergeWith(2..5))
+            assertEquals(1..10, (1..7).mergeWith(4..10))
+            assertEquals(1..10, (9..10).mergeWith(1..9))
+        }
+    }
+}

src/test/kotlin/lv/esupe/aoc/utils/RangeTest.kt

@@ -0,0 +1,13 @@
+package lv.esupe.aoc.year2025
+
+import lv.esupe.aoc.DayTest
+import org.junit.jupiter.api.Test
+
+class Day5Test : DayTest<Int, Long>() {
+    override val puzzle = { Day5() }
+
+    @Test
+    fun day5_1() {
+        runTest("_1", 3, 14)
+    }
+}

src/test/kotlin/lv/esupe/aoc/year2025/Day5Test.kt

@@ -0,0 +1,11 @@
+3-5
+10-14
+16-20
+12-18
+
+1
+5
+8
+11
+17
+32