2024 - Day 17 - part 1&2 - the latter more or less copied from the ko…

…tlin-slack-aoc-channel.

src/main/kotlin/no/rodland/advent_2024/Day17.kt

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+package no.rodland.advent_2024
+
+import no.rodland.advent.Day
+
+// template generated: 17/12/2024
+// Fredrik Rødland 2024
+
+class Day17(val input: List<String>) : Day<String, Long, Day17.Computer> {
+    private val comp = input.parse()
+
+    override fun partOne(): String {
+        return comp.run()
+    }
+
+    // solution more-or-less from: https://kotlinlang.slack.com/archives/C87V9MQFK/p1734411603798899
+    override fun partTwo(): Long {
+        return recurse(comp.opcodes)
+    }
+
+    private fun recurse(target: List<Int>): Long {
+        var a = if (target.size == 1) 0 else recurse(target.drop(1)) shl 3
+        while (comp.copy(a = a).run() != target.joinToString(",")) {
+            a++
+        }
+        return a
+    }
+
+    fun run(a: Long): String = comp.copy(a = a).run()
+
+    data class Computer(var a: Long, var b: Long, var c: Long, val opcodes: List<Int>) {
+        private var ip = 0
+        private val output = mutableListOf<Int>()
+
+        fun output() = output.joinToString(",")
+        fun output(operand: Int) = output.add(operand)
+
+        private fun combo(i: Int): Long {
+            return when (i) {
+                in 0..3 -> i.toLong()
+                4 -> a
+                5 -> b
+                6 -> c
+                7 -> error("Reserved combo operand: $i")
+                else -> error("Invalid combo operand: $i")
+            }
+        }
+
+        fun run(): String {
+            while (ip < opcodes.size) {
+                val opcode = opcodes[ip]
+                val operand = opcodes[ip + 1]
+                when (opcode) {
+                    0 -> a = a shr combo(operand).toInt()
+                    1 -> b = b xor operand.toLong()
+                    2 -> b = combo(operand) % 8
+                    3 -> if (a != 0L) ip = operand - 2
+                    4 -> b = b xor c
+                    5 -> output((combo(operand) % 8).toInt())
+                    6 -> b = a shr combo(operand).toInt()
+                    7 -> c = a shr combo(operand).toInt()
+                    else -> error("Invalid opcode: $opcode")
+                }
+                ip += 2
+            }
+            return output()
+        }
+    }
+
+    override fun List<String>.parse(): Computer {
+        val a = get(0).substringAfter("A: ").toLong()
+        val b = get(1).substringAfter("B: ").toLong()
+        val c = get(2).substringAfter("C: ").toLong()
+        val op = get(4).substringAfter("Program: ").split(",").map { it.toInt() }
+        return Computer(a, b, c, op)
+    }
+
+    override val day = "17".toInt()
+}

src/test/kotlin/no/rodland/advent_2024/Day17Test.kt

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+package no.rodland.advent_2024
+
+import no.rodland.advent.*
+import org.junit.jupiter.api.Nested
+import org.junit.jupiter.api.Test
+import readFile
+
+//
+//  run: download_aoc_input.sh to download input
+//
+
+@Suppress("ClassName", "SpellCheckingInspection")
+@DisableSlow
+internal class Day17Test {
+    private val data17 = "2024/input_17.txt".readFile()
+    private val test17 = "2024/input_17_test.txt".readFile()
+    private val test17Part2 = "2024/input_17_test_part2.txt".readFile()
+
+    private val resultTestOne = "4,6,3,5,6,3,5,2,1,0"
+    private val resultTestTwo = 117440L
+    private val resultOne = "4,0,4,7,1,2,7,1,6"
+    private val resultTwo = 202322348616234L
+
+    val test = run {
+        val liveDay = Day17(data17)
+        val testDay = Day17(test17)
+        val testDayPart2 = Day17(test17Part2)
+        AOCTestSuite<Any?, Unit, Unit>(
+            AOCTest({ liveDay.partOne() }, Unit, resultOne, 1000, liveDay.day, Part.ONE, true),
+            AOCTest({ liveDay.partTwo() }, Unit, resultTwo, 1000, liveDay.day, Part.TWO, true),
+            AOCTest({ testDay.partOne() }, Unit, resultTestOne, 1, liveDay.day, Part.ONE, false),
+            AOCTest({ testDayPart2.partTwo() }, Unit, resultTestTwo, 1, liveDay.day, Part.TWO, false),
+            AOCTest<Unit, Unit>({ Day17(data17) }, Unit, Unit, 100, liveDay.day, Part.INIT, live = true),
+            AOCTest<Unit, Unit>({ Day17(test17Part2) }, Unit, Unit, 100, liveDay.day, Part.INIT, live = false),
+        )
+    }
+
+    @Nested
+    inner class Init {
+        @Test
+        fun `17,-,bst,1`() {
+            val computer = Day17.Computer(0, 0, 9, listOf(2, 6))
+            computer.run({ computer.b }, 1)
+        }
+
+        @Test
+        fun `17,-,out,1`() {
+            val computer = Day17.Computer(10, 0, 0, listOf(5, 0, 5, 1, 5, 4))
+            computer.run({ computer.output() }, "0,1,2")
+        }
+
+        @Test
+        fun `17,-,out2,1`() {
+            val computer = Day17.Computer(2024, 0, 0, listOf(0, 1, 5, 4, 3, 0))
+            computer.run({ computer.output() to computer.a }, "4,2,5,6,7,7,7,7,3,1,0" to 0L)
+        }
+
+        @Test
+        fun `17,-,bxl,1`() {
+            val computer = Day17.Computer(0, 29, 0, listOf(1, 7))
+            computer.run({ computer.b }, 26)
+        }
+
+        @Test
+        fun `17,-,bxc,1`() {
+            val computer = Day17.Computer(0, 2024, 43690, listOf(4, 0))
+            computer.run({ computer.b }, 44354)
+        }
+
+        @Test
+        fun `17,-,original,1`() {
+            val org = listOf(0, 3, 5, 4, 3, 0)
+            val computer = Day17.Computer(117440, 0, 0, org)
+            computer.run({ computer.output() }, org.joinToString(","))
+        }
+
+        private fun <T> Day17.Computer.run(function: (Unit) -> T, expected: T, part: Part = Part.ONE) {
+            run()
+            report(AOCTest(function, Unit, expected, 1, "17".toInt(), part, false, "2,6"))
+        }
+
+        @Test
+        fun `17,-,example,1`() {
+            report(AOCTest({ "123".toInt() }, Unit, 123, 5, "17".toInt(), Part.TWO, false, "example"))
+        }
+
+        @Test
+        fun `17,-,example,2`() {
+            report(test.initTest.copy())
+        }
+
+        @Test
+        fun `17,-,test,init`() {
+            report(test.initTest)
+        }
+
+        @Test
+        fun `17,-,live,init`() {
+            report(test.initLive)
+        }
+    }
+
+    @Nested
+    inner class `Part 1` {
+        @Test
+        fun `17,1,test`() {
+            report(test.testPart1)
+        }
+
+        @Test
+        fun `17,1,live,1`() {
+            report(test.livePart1)
+        }
+    }
+
+    @Nested
+    inner class `Part 2` {
+        @Test
+        fun `17,2,test`() {
+            report(test.testPart2)
+        }
+
+        @Test
+        fun `17,2,live,1`() {
+            report(test.livePart2)
+        }
+    }
+}

src/test/resources/2024/input_17_test.txt

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+Register A: 729
+Register B: 0
+Register C: 0
+
+Program: 0,1,5,4,3,0

src/test/resources/2024/input_17_test_part2.txt

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+Register A: 2024
+Register B: 0
+Register C: 0
+
+Program: 0,3,5,4,3,0