Merge pull request #8 from jwnace/day04

Day04

src/main/kotlin/day01/day01.kt

@@ -16,15 +16,15 @@ private val digitStrings = mapOf(
     "nine" to 9,
 )
 
-fun solve1() = part1(input)
+fun part1() = solve1(input)
 
-fun solve2() = part2(input)
+fun part2() = solve2(input)
 
-fun part1(input: List<String>): Int =
+fun solve1(input: List<String>): Int =
     input.map { line -> line.filter { c -> c.isDigit() } }
         .sumOf { "${it.first()}${it.last()}".toInt() }
 
-fun part2(input: List<String>): Int {
+fun solve2(input: List<String>): Int {
     var sum = 0
 
     for (line in input) {

src/main/kotlin/day02/day02.kt

@@ -8,15 +8,15 @@ const val BLUE_CUBES = 14
 
 val input = File("src/main/kotlin/day02/input.txt").readLines()
 
-fun solve1() = part1(input)
+fun part1() = solve1(input)
 
-fun solve2() = part2(input)
+fun part2() = solve2(input)
 
-fun part1(input: List<String>): Int =
+fun solve1(input: List<String>): Int =
     input.map { line -> Game.parse(line) }
         .filter { it.isPossible }
         .sumOf { it.id }
 
-fun part2(input: List<String>): Int =
+fun solve2(input: List<String>): Int =
     input.map { Game.parse(it) }
         .sumOf { it.power }

src/main/kotlin/day03/day03.kt

@@ -4,18 +4,18 @@ import java.io.File
 
 val input = File("src/main/kotlin/day03/input.txt").readLines()
 
-fun solve1() = part1(input)
+fun part1() = solve1(input)
 
-fun solve2() = part2(input)
+fun part2() = solve2(input)
 
-fun part1(input: List<String>): Int {
+fun solve1(input: List<String>): Int {
     val grid = buildGrid(input)
     val partNumbers = getPartNumbers(grid)
 
     return partNumbers.sumOf { it.number }
 }
 
-fun part2(input: List<String>): Int {
+fun solve2(input: List<String>): Int {
     val grid = buildGrid(input)
     val partNumbers = getPartNumbers(grid)
 

src/main/kotlin/day04/ScratchCard.kt

@@ -0,0 +1,21 @@
+package day04
+
+import kotlin.math.pow
+
+class ScratchCard(val cardNumber: Int, winningNumbersList: Set<Int>, numbersYouHaveList: Set<Int>) {
+    companion object {
+        fun parse(line: String): ScratchCard {
+            val (left, right) = line.split(": ")
+            val cardNumber = left.substring(5).trim().toInt()
+            val (winningNumbers, numbersYouHave) = right.split(" | ").map { numbers ->
+                numbers.split(" ").filter { it.isNotEmpty() }.map { it.toInt() }.toSet()
+            }
+
+            return ScratchCard(cardNumber, winningNumbers, numbersYouHave)
+        }
+    }
+
+    val winCount = winningNumbersList.intersect(numbersYouHaveList).count()
+
+    val score = (2.0).pow((winCount - 1).toDouble()).toInt()
+}

src/main/kotlin/day04/day04.kt

@@ -0,0 +1,29 @@
+package day04
+
+import java.io.File
+
+val input = File("src/main/kotlin/day04/input.txt").readLines()
+
+fun part1() = solve1(input)
+
+fun part2() = solve2(input)
+
+fun solve1(input: List<String>): Int = input.map { ScratchCard.parse(it) }.sumOf { it.score }
+
+fun solve2(input: List<String>): Int {
+    val cards = input.map { ScratchCard.parse(it) }
+    val cardCounts = cards.associate { it.cardNumber to 1 }.toMutableMap()
+    val minCardNumber = cards.minOf { it.cardNumber }
+    val maxCardNumber = cards.maxOf { it.cardNumber }
+
+    for (cardNumber in minCardNumber..maxCardNumber) {
+        val card = cards.find { it.cardNumber == cardNumber } ?: continue
+        val cardCount = cardCounts[cardNumber] ?: continue
+
+        for (j in 1..card.winCount) {
+            cardCounts[cardNumber + j] = cardCounts[cardNumber + j]!! + cardCount
+        }
+    }
+
+    return cardCounts.values.sum()
+}

src/main/kotlin/main.kt

@@ -1,8 +1,10 @@
 fun main() {
-    println("day 01, part 1: ${day01.solve1()}")
-    println("day 01, part 2: ${day01.solve2()}")
-    println("day 02, part 1: ${day02.solve1()}")
-    println("day 02, part 2: ${day02.solve2()}")
-    println("day 03, part 1: ${day03.solve1()}")
-    println("day 03, part 2: ${day03.solve2()}")
+    println("day 01, part 1: ${day01.part1()}")
+    println("day 01, part 2: ${day01.part2()}")
+    println("day 02, part 1: ${day02.part1()}")
+    println("day 02, part 2: ${day02.part2()}")
+    println("day 03, part 1: ${day03.part1()}")
+    println("day 03, part 2: ${day03.part2()}")
+    println("day 04, part 1: ${day04.part1()}")
+    println("day 04, part 2: ${day04.part2()}")
 }

src/test/kotlin/day01/Day01Tests.kt

@@ -15,15 +15,15 @@ class Day01Tests {
         )
 
         // act
-        val actual = part1(input)
+        val actual = solve1(input)
 
         // assert
         assertEquals(142, actual)
     }
 
     @Test
     fun `part1 solution`() {
-        assertEquals(55208, solve1())
+        assertEquals(55208, part1())
     }
 
     @Test
@@ -40,14 +40,14 @@ class Day01Tests {
         )
 
         // act
-        val actual = part2(input)
+        val actual = solve2(input)
 
         // assert
         assertEquals(281, actual)
     }
 
     @Test
     fun `part2 solution`() {
-        assertEquals(54578, solve2())
+        assertEquals(54578, part2())
     }
 }

src/test/kotlin/day02/Day02Tests.kt

@@ -16,15 +16,15 @@ class Day02Tests {
         )
 
         // act
-        val actual = part1(input)
+        val actual = solve1(input)
 
         // assert
         assertEquals(8, actual)
     }
 
     @Test
     fun `part1 solution`() {
-        assertEquals(2348, solve1())
+        assertEquals(2348, part1())
     }
 
     @Test
@@ -39,14 +39,14 @@ class Day02Tests {
         )
 
         // act
-        val actual = part2(input)
+        val actual = solve2(input)
 
         // assert
         assertEquals(2286, actual)
     }
 
     @Test
     fun `part2 solution`() {
-        assertEquals(76008, solve2())
+        assertEquals(76008, part2())
     }
 }

src/test/kotlin/day03/Day03Tests.kt

@@ -21,15 +21,15 @@ class Day03Tests {
         )
 
         // act
-        val actual = part1(input)
+        val actual = solve1(input)
 
         // assert
         assertEquals(4361, actual)
     }
 
     @Test
     fun `part1 solution`() {
-        assertEquals(514969, solve1())
+        assertEquals(514969, part1())
     }
 
     @Test
@@ -49,14 +49,14 @@ class Day03Tests {
         )
 
         // act
-        val actual = part2(input)
+        val actual = solve2(input)
 
         // assert
         assertEquals(467835, actual)
     }
 
     @Test
     fun `part2 solution`() {
-        assertEquals(78915902, solve2())
+        assertEquals(78915902, part2())
     }
 }

src/test/kotlin/day04/Day04Tests.kt

@@ -0,0 +1,54 @@
+package day04
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+
+class Day04Tests {
+    @Test
+    fun `part1 example`() {
+        // arrange
+        val input = listOf(
+            "Card 1: 41 48 83 86 17 | 83 86  6 31 17  9 48 53",
+            "Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19",
+            "Card 3:  1 21 53 59 44 | 69 82 63 72 16 21 14  1",
+            "Card 4: 41 92 73 84 69 | 59 84 76 51 58  5 54 83",
+            "Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36",
+            "Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11",
+        )
+
+        // act
+        val actual = solve1(input)
+
+        // assert
+        assertEquals(13, actual)
+    }
+
+    @Test
+    fun `part1 solution`() {
+        assertEquals(21158, part1())
+    }
+
+    @Test
+    fun `part2 example`() {
+        // arrange
+        val input = listOf(
+            "Card 1: 41 48 83 86 17 | 83 86  6 31 17  9 48 53",
+            "Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19",
+            "Card 3:  1 21 53 59 44 | 69 82 63 72 16 21 14  1",
+            "Card 4: 41 92 73 84 69 | 59 84 76 51 58  5 54 83",
+            "Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36",
+            "Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11",
+        )
+
+        // act
+        val actual = solve2(input)
+
+        // assert
+        assertEquals(30, actual)
+    }
+
+    @Test
+    fun `part2 solution`() {
+        assertEquals(6050769, part2())
+    }
+}