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Clean up 2024 day 17
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@sim642
sim642 committed Dec 17, 2024
1 parent 2a53752 commit 1966a7c
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Showing 2 changed files with 38 additions and 42 deletions.
70 changes: 33 additions & 37 deletions src/main/scala/eu/sim642/adventofcode2024/Day17.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -7,30 +7,24 @@ import scala.jdk.CollectionConverters.*

object Day17 {

case class Registers(a: Int, b: Int, c: Int)
case class Registers(a: Long, b: Long, c: Long) // Long registers for simulating part 2

type Program = Seq[Int]
type Program = Seq[Byte]

case class Input(registers: Registers, program: Program)

def runOutput0(input: Input): Seq[Int] = {
val Input(registers, program) = input
def runOutputs(registers: Registers, program: Program): LazyList[Byte] = {

def helper(ip: Int, registers: Registers): LazyList[Int] = {
//println(ip)
//println(registers)
def helper(ip: Int, registers: Registers): LazyList[Byte] = {

def combo(operand: Int): Int = operand match {
def combo(operand: Byte): Long = operand match {
case 0 | 1 | 2 | 3 => operand
case 4 => registers.a
case 5 => registers.b
case 6 => registers.c
case 7 => throw new IllegalArgumentException("illegal combo operand")
}

// 0, 5, 3
// 2 1 7 4

if (program.indices.contains(ip)) {
lazy val literalOperand = program(ip + 1)
lazy val comboOperand = combo(literalOperand)
Expand All @@ -48,7 +42,7 @@ object Day17 {
case 4 => // bxc
helper(ip + 2, registers.copy(b = registers.b ^ registers.c))
case 5 => // out
(comboOperand & 0b111) #:: helper(ip + 2, registers)
(comboOperand & 0b111).toByte #:: helper(ip + 2, registers)
case 6 => // bdv
//helper(ip + 2, registers.copy(b = registers.a / (1 << comboOperand)))
helper(ip + 2, registers.copy(b = registers.a >> comboOperand))
Expand All @@ -65,22 +59,24 @@ object Day17 {
helper(0, registers)
}

def runOutput(input: Input): String = runOutput0(input).mkString(",")
def runOutputsString(input: Input): String =
runOutputs(input.registers, input.program).mkString(",")

trait Part2Solution {
def findQuineA(input: Input): Long
}

object NaivePart2Solution extends Part2Solution {
override def findQuineA(input: Input): Long = {
val Input(registers, program) = input
Iterator.from(0)
.find(newA => runOutput0(Input(input.registers.copy(a = newA), input.program)) == input.program)
.find(newA => runOutputs(registers.copy(a = newA), program) == program) // TODO: does equality check stop running on first mismatch?
.get
}
}

object SemiNaivePart2Solution extends Part2Solution {
def myProg(initialA: Int, expectedOutputs: Iterator[Int]): Boolean = {
def myProg(initialA: Int, expectedOutputs: Iterator[Byte]): Boolean = {
var a: Int = initialA
var b: Int = 0
var c: Int = 0
Expand All @@ -106,14 +102,15 @@ object Day17 {

object ReverseEngineeredZ3Part2Solution extends Part2Solution {
override def findQuineA(input: Input): Long = {
val Seq(2,4,1,bxl1,7,5,1,bxl2,4,5,0,3,5,5,3,0) = input.program
val Seq(2, 4, 1, bxl1, 7, 5, 1, bxl2, 4, 5, 0, 3, 5, 5, 3, 0) = input.program // TODO: doesn't support other orders of some operations

val ctx = new Context(Map("model" -> "true").asJava)
import ctx._
val s = mkSolver()
val s = mkOptimize()

val bits = input.program.size * 3
val initialA = mkBVConst("initialA", bits)
s.MkMinimize(initialA)

for ((instruction, i) <- input.program.zipWithIndex) {
val a = mkBVLSHR(initialA, mkBV(i * 3, bits))
Expand All @@ -123,11 +120,10 @@ object Day17 {
b = mkBVXOR(b, mkBV(bxl2, bits))
b = mkBVXOR(b, c)
val out = mkBVAND(b, mkBV(0b111, bits))
s.add(mkEq(out, mkBV(instruction, bits)))
s.Add(mkEq(out, mkBV(instruction, bits)))
}

assert(s.check() == Status.SATISFIABLE)
// TODO: minimize
assert(s.Check() == Status.SATISFIABLE)
s.getModel.evaluate(initialA, false).toString.toLong
}
}
Expand All @@ -137,22 +133,22 @@ object Day17 {
*/
object GenericZ3Part2Solution extends Part2Solution {
override def findQuineA(input: Input): Long = {
val Input(registers, program) = input

val ctx = new Context(Map("model" -> "true").asJava)
import ctx._
val s = mkOptimize()

case class Registers(a: BitVecExpr, b: BitVecExpr, c: BitVecExpr)

val Input(registers, program) = input
val bits = input.program.size * 3

val zeroBV = mkBV(0, bits)
val threeBitBV = mkBV(0b111, bits)

// copied & modified from part 1
def helper(ip: Int, registers: Registers, expectedOutputs: List[Int]): BoolExpr = {
def helper(ip: Int, registers: Registers, expectedOutputs: List[Byte]): BoolExpr = {

def combo(operand: Int): BitVecExpr = operand match {
def combo(operand: Byte): BitVecExpr = operand match {
case 0 | 1 | 2 | 3 => mkBV(operand, bits)
case 4 => registers.a
case 5 => registers.b
Expand Down Expand Up @@ -180,7 +176,7 @@ object Day17 {
helper(ip + 2, registers.copy(b = mkBVXOR(registers.b, registers.c)), expectedOutputs)
case 5 => // out
expectedOutputs match {
case Nil => mkFalse()
case Nil => mkFalse() // does not expect more outputs
case expectedOutput :: newExpectedOutputs =>
mkAnd(
mkEq(mkBVAND(comboOperand, threeBitBV), mkBV(expectedOutput, bits)),
Expand All @@ -197,16 +193,17 @@ object Day17 {
else {
expectedOutputs match {
case Nil => mkTrue()
case _ :: _ => mkFalse()
case _ :: _ => mkFalse() // expects more outputs
}
}
}

val initialA = mkBVConst("initialA", bits)
val constraint = helper(0, Registers(initialA, zeroBV, zeroBV), program.toList)
s.Add(constraint)
s.MkMinimize(initialA)

val constraint = helper(0, Registers(initialA, mkBV(registers.b, bits), mkBV(registers.c, bits)), program.toList)
s.Add(constraint)

assert(s.Check() == Status.SATISFIABLE)
s.getModel.evaluate(initialA, false).toString.toLong
}
Expand All @@ -217,38 +214,37 @@ object Day17 {
val iterProgram :+ 3 :+ 0 = input.program

@tailrec
def helper(as: Set[Long], expectedOutputsRev: List[Int]): Set[Long] = expectedOutputsRev match {
def helper(as: Set[Long], expectedOutputsRev: List[Byte]): Set[Long] = expectedOutputsRev match {
case Nil => as
case expectedOutput :: newExpectedOutputsRev =>
val newAs =
for {
a <- as
aStep <- 0 to 7
newA = (a << 3) | aStep
out = runOutput0(Input(Registers((newA & 0b1111111111).toInt, 0, 0), iterProgram))
if out == Seq(expectedOutput)
iterA <- 0 to 7
newA = (a << 3) | iterA
outputs = runOutputs(input.registers.copy(a = newA), iterProgram)
if outputs == Seq(expectedOutput)
} yield newA
helper(newAs, newExpectedOutputsRev)
}

val as = helper(Set(0), input.program.reverse.toList)
//as.foreach(println)
as.min
}
}

def parseInput(input: String): Input = input match {
case s"Register A: $a\nRegister B: $b\nRegister C: $c\n\nProgram: $programStr" =>
val registers = Registers(a.toInt, b.toInt, c.toInt)
val program = programStr.split(",").map(_.toInt).toSeq
val program = programStr.split(",").map(_.toByte).toSeq
Input(registers, program)
}

lazy val input: String = scala.io.Source.fromInputStream(getClass.getResourceAsStream("day17.txt")).mkString.trim

def main(args: Array[String]): Unit = {
import GenericZ3Part2Solution._
println(runOutput(parseInput(input)))
import ReverseEngineeredPart2Solution._
println(runOutputsString(parseInput(input)))
println(findQuineA(parseInput(input)))

// part 1: 4,5,0,4,7,4,3,0,0 - wrong (bst used literal not combo operand)
Expand Down
10 changes: 5 additions & 5 deletions src/test/scala/eu/sim642/adventofcode2024/Day17Test.scala
View file
Original file line number Diff line number Diff line change
Expand Up @@ -47,13 +47,13 @@ object Day17Test {

class Part1Test extends AnyFunSuite {
test("Part 1 examples") {
assert(runOutput(parseInput(exampleInput)) == "4,6,3,5,6,3,5,2,1,0")
assert(runOutput(parseInput(exampleInput1)) == "0,1,2")
assert(runOutput(parseInput(exampleInput2)) == "4,2,5,6,7,7,7,7,3,1,0")
assert(runOutputsString(parseInput(exampleInput)) == "4,6,3,5,6,3,5,2,1,0")
assert(runOutputsString(parseInput(exampleInput1)) == "0,1,2")
assert(runOutputsString(parseInput(exampleInput2)) == "4,2,5,6,7,7,7,7,3,1,0")
}

test("Part 1 input answer") {
assert(runOutput(parseInput(input)) == "4,3,2,6,4,5,3,2,4")
assert(runOutputsString(parseInput(input)) == "4,3,2,6,4,5,3,2,4")
}
}

Expand All @@ -75,5 +75,5 @@ object Day17Test {

class GenericZ3Part2SolutionTest extends Part2SolutionExampleTest(GenericZ3Part2Solution) with Part2SolutionInputTest(GenericZ3Part2Solution)

class ReverseEngineeredPart2SolutionTest extends Part2SolutionInputTest(ReverseEngineeredPart2Solution)
class ReverseEngineeredPart2SolutionTest extends Part2SolutionExampleTest(ReverseEngineeredPart2Solution) with Part2SolutionInputTest(ReverseEngineeredPart2Solution)
}

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