From 0f2098634bf395f3c3631813fb476161d7fd3043 Mon Sep 17 00:00:00 2001
From: Hubert Van De Walle <hubv@protonmail.com>
Date: Fri, 18 Dec 2020 13:55:19 +0100
Subject: [PATCH] Parallelize solutions + benchmarks

---
 days/build.gradle.kts                  |  3 ++
 days/src/main/kotlin/Day18.kt          | 42 +++++++++++++++---------
 days/src/test/kotlin/Day18Benchmark.kt | 44 ++++++++++++++++++++++++++
 3 files changed, 74 insertions(+), 15 deletions(-)
 create mode 100644 days/src/test/kotlin/Day18Benchmark.kt

diff --git a/days/build.gradle.kts b/days/build.gradle.kts
index 6eb33d2..9ed4323 100644
--- a/days/build.gradle.kts
+++ b/days/build.gradle.kts
@@ -11,6 +11,9 @@ dependencies {
     implementation(Libs.Micronaut.kotlin)
     kapt(Libs.Micronaut.processor)
 
+    implementation(Libs.Slf4J.api)
+    runtimeOnly(Libs.Slf4J.simple)
+
     implementation(Libs.eclipseCollections) {
         because("Primitive collections mostly")
     }
diff --git a/days/src/main/kotlin/Day18.kt b/days/src/main/kotlin/Day18.kt
index 6befef1..db10b0b 100644
--- a/days/src/main/kotlin/Day18.kt
+++ b/days/src/main/kotlin/Day18.kt
@@ -5,6 +5,8 @@ import be.vandewalleh.aoc.utils.input.Input
 import be.vandewalleh.aoc.utils.input.Lines
 import be.vandewalleh.aoc.utils.input.createDay
 import java.util.*
+import org.slf4j.Logger
+import org.slf4j.LoggerFactory
 
 enum class Operator { Add, Multiply }
 
@@ -13,10 +15,15 @@ operator fun Operator.invoke(a: Long, b: Long) = when (this) {
     Operator.Multiply -> a * b
 }
 
+private inline fun Logger.debug(msg: () -> Any) {
+    if (isDebugEnabled) debug(msg().toString())
+}
+
 @Day(18)
 class Day18(@Lines val input: Input<List<String>>) {
 
-    val lines = input.value.map { it.replace(" ", "") }
+    private val logger = LoggerFactory.getLogger("Day18")
+    private val lines = input.value.map { it.replace(" ", "") }
 
     private fun parseGroups(line: String): Map<Int, List<IntRange>> {
         var depth = 0
@@ -37,16 +44,15 @@ class Day18(@Lines val input: Input<List<String>>) {
             }
         }
 
-        check(openingPars.isEmpty())
-        return groups.also { println(it) }
+        return groups.also { logger.debug { it } }
     }
 
     private fun solveGroup(group: String, precedence: Boolean) = solveGroup(parseGroup(group), precedence)
 
     private fun solveGroup(group: Pair<LinkedList<Long>, LinkedList<Operator>>, precedence: Boolean): Long {
         val (operands, operators) = group
-        println(operands)
-        println(operators)
+        logger.debug { operands }
+        logger.debug { operators }
 
         if (!precedence) {
             for (i in operators.indices) {
@@ -64,19 +70,18 @@ class Day18(@Lines val input: Input<List<String>>) {
             var i = 0
             while (operators.any { it == Operator.Add }) {
 
-                val a = operands[i]
-                val b = operands[i + 1]
                 val operator = operators[i]
 
                 if (operator == Operator.Add) {
+                    val a = operands[i]
+                    val b = operands[i + 1]
                     val res = operator(a, b)
                     operands.removeAt(i)
                     operands[i] = res
                     operators.removeAt(i)
-                    i--
+                } else {
+                    i++
                 }
-
-                i++
             }
 
             return operands.reduce { a, b -> Operator.Multiply(a, b) }
@@ -105,8 +110,6 @@ class Day18(@Lines val input: Input<List<String>>) {
 
         operands.add(operand.toString().toLong())
 
-        check(operands.size == operators.size + 1)
-        check(operators.isNotEmpty())
         return Pair(operands, operators)
     }
 
@@ -117,7 +120,7 @@ class Day18(@Lines val input: Input<List<String>>) {
             val groups = parseGroups(l)
             if (groups.isEmpty()) break
 
-            val highestDepth = groups.keys.sorted().maxOrNull()!!
+            val highestDepth = groups.keys.maxOrNull()!!
             val solvableRanges = groups[highestDepth]!!
 
             val solved = ArrayDeque<Pair<IntRange, Long>>()
@@ -155,8 +158,17 @@ class Day18(@Lines val input: Input<List<String>>) {
         return solveGroup(l, precedence)
     }
 
-    fun part1() = lines.sumOf { solveLine(it) }
-    fun part2() = lines.sumOf { solveLine(it, precedence = true) }
+    fun part1() = lines
+        .parallelStream()
+        .map { solveLine(it) }
+        .reduce { t, u -> t + u }
+        .get()
+
+    fun part2() = lines
+        .parallelStream()
+        .map { solveLine(it, precedence = true) }
+        .reduce { t, u -> t + u }
+        .get()
 }
 
 fun main() = with(createDay<Day18>()) {
diff --git a/days/src/test/kotlin/Day18Benchmark.kt b/days/src/test/kotlin/Day18Benchmark.kt
new file mode 100644
index 0000000..8e75528
--- /dev/null
+++ b/days/src/test/kotlin/Day18Benchmark.kt
@@ -0,0 +1,44 @@
+package be.vandewalleh.aoc.days
+
+import be.vandewalleh.aoc.utils.input.createDay
+import java.util.concurrent.TimeUnit
+import org.openjdk.jmh.annotations.*
+import org.openjdk.jmh.infra.Blackhole
+import org.openjdk.jmh.runner.Runner
+import org.openjdk.jmh.runner.options.OptionsBuilder
+
+/*
+Benchmark             Mode  Cnt  Score   Error  Units
+Day18Benchmark.part1  avgt    3  0.253 ± 0.098  ms/op
+Day18Benchmark.part2  avgt    3  0.283 ± 0.027  ms/op
+*/
+
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+@State(Scope.Benchmark)
+@Warmup(iterations = 1)
+@Measurement(iterations = 3)
+open class Day18Benchmark {
+
+    private val day18 = createDay<Day18>()
+
+    @Benchmark
+    fun part1(blackhole: Blackhole) {
+        blackhole.consume(day18.part1())
+    }
+
+    @Benchmark
+    fun part2(blackhole: Blackhole) {
+        blackhole.consume(day18.part2())
+    }
+
+}
+
+fun main() {
+    val opt = OptionsBuilder()
+        .include(Day18Benchmark::class.simpleName)
+        .forks(1)
+        .build()
+
+    Runner(opt).run()
+}