Add solution for Y2024D22.

Author: Jadarma

Diff for: README.md

@@ -15,7 +15,7 @@ _"Anything that's worth doing, is worth overdoing."_
 Table of contents to jump straight to the problem you're looking for.
 
 <details open>
-    <summary>2024 (42x⭐)</summary>
+    <summary>2024 (44x⭐)</summary>
 
 | Day | Title                                                       | Stars |
 |:---:|:------------------------------------------------------------|:-----:|
@@ -40,6 +40,7 @@ Table of contents to jump straight to the problem you're looking for.
 | 19  | [Linen Layout](solutions/aockt/y2024/Y2024D19.kt)           |  ⭐⭐   |
 | 20  | [Race Condition](solutions/aockt/y2024/Y2024D20.kt)         |  ⭐⭐   |
 | 21  | [Keypad Conundrum](solutions/aockt/y2024/Y2024D21.kt)       |  ⭐⭐   |
+| 22  | [Monkey Market](solutions/aockt/y2024/Y2024D22.kt)          |  ⭐⭐   |
 
 </details>
 

Diff for: inputs/aockt/y2024/d22/input.txt

@@ -0,0 +1,42 @@
+package aockt.y2024
+
+import aockt.util.parse
+import io.github.jadarma.aockt.core.Solution
+
+object Y2024D22 : Solution {
+
+    /** Generate a pseudo-random sequence of numbers from the starting [seed]. */
+    private fun pseudoRandom(seed: Long): Sequence<Long> = generateSequence(seed) {
+        var result = it
+        result = result xor (result shl 6 ) and 0xFFFFFF
+        result = result xor (result shr 5 ) and 0xFFFFFF
+        result = result xor (result shl 11) and 0xFFFFFF
+        result
+    }
+
+    /** Return the buyer prices from a given trader [seed], with a limit of how many secrets to generate [perDay]. */
+    private fun buyerPrices(seed: Long, perDay: Int = 2000): Sequence<Int> =
+        pseudoRandom(seed)
+            .take(perDay + 1)
+            .map { (it % 10).toInt() }
+
+    /** Parse the [input] and return the initial seed for each monkey buyer. */
+    private fun parseInput(input: String): List<Long> = parse { input.lines().map(String::toLong) }
+
+    override fun partOne(input: String): Long = parseInput(input).sumOf { pseudoRandom(it).drop(2000).first() }
+
+    override fun partTwo(input: String): Int =
+        buildMap {
+            for (seed in parseInput(input)) {
+                val seen = mutableSetOf<List<Int>>()
+                for ((a, b, c, d, e) in buyerPrices(seed).windowed(size = 5)) {
+                    val sequence = listOf(b - a, c - b, d - c, e - d)
+                        .takeIf { it !in seen }
+                        ?.also(seen::add)
+                        ?: continue
+
+                    compute(sequence) { _, v -> (v ?: 0) + e }
+                }
+            }
+        }.maxOf { it.value }
+}

Diff for: inputs/aockt/y2024/d22/solution_part1.txt

@@ -0,0 +1,21 @@
+package aockt.y2024
+
+import io.github.jadarma.aockt.test.AdventDay
+import io.github.jadarma.aockt.test.AdventSpec
+
+@AdventDay(2024, 22, "Monkey Market")
+class Y2024D22Test : AdventSpec<Y2024D22>({
+
+    val example1 = listOf(1, 10, 100, 2024).joinToString(separator = "\n")
+    val example2 = listOf(1, 2, 3, 2024).joinToString(separator = "\n")
+
+    partOne {
+        example1 shouldOutput 37_327_623
+        example2 shouldOutput 37_990_510
+    }
+
+    partTwo {
+        example1 shouldOutput 24
+        example2 shouldOutput 23
+    }
+})