Day08

2020-12-08 07:30:51 +01:00
parent f2280bc2b5
commit 7d8db7b493
2 changed files with 720 additions and 0 deletions
@@ -0,0 +1,71 @@
+package be.vandewalleh.aoc.days
+
+import be.vandewalleh.aoc.utils.input.Day
+import be.vandewalleh.aoc.utils.input.Input
+import be.vandewalleh.aoc.utils.input.Lines
+import be.vandewalleh.aoc.utils.input.createDay
+import org.eclipse.collections.impl.factory.primitive.IntLists
+import org.eclipse.collections.impl.factory.primitive.IntSets
+
+@Day(8)
+class Day08(@Lines val input: Input<List<String>>) {
+
+    private val instructions = input.value
+        .map {
+            val words = it.split(" ")
+            Instruction(Operation.valueOf(words[0].capitalize()), words[1].toInt())
+        }.toTypedArray()
+
+    fun part1() = run(instructions)
+
+    private fun run(mutatedInstructions: Array<Instruction>): Int {
+        var acc = 0
+        var ptr = 0
+
+        val visited = IntSets.mutable.empty()
+
+        while (visited.add(ptr)) {
+            val instruction = mutatedInstructions[ptr]
+            when (instruction.operation) {
+                Operation.Acc -> {
+                    acc += instruction.argument
+                    ptr++
+                }
+                Operation.Jmp -> ptr += instruction.argument
+                Operation.Nop -> ptr++
+            }
+            if (ptr !in mutatedInstructions.indices) {
+                println(acc)
+                error("oob")
+            }
+        }
+
+        return acc
+    }
+
+    fun part2() {
+        val possibleMutations = IntLists.mutable.empty()
+        instructions.forEachIndexed { i, e ->
+            if (e.operation != Operation.Acc) possibleMutations.add(i)
+        }
+
+        possibleMutations.forEach { index ->
+            val copy = instructions.clone().also {
+                val modifiedOperation = if (it[index].operation == Operation.Nop) Operation.Jmp else Operation.Nop
+                it[index] = it[index].copy(operation = modifiedOperation)
+            }
+            run(copy)
+        }
+    }
+
+}
+
+enum class Operation { Acc, Jmp, Nop }
+
+data class Instruction(val operation: Operation, val argument: Int)
+
+fun main() {
+    val day = createDay<Day08>()
+    println(day.part1())
+    println(day.part2())
+}