Solution Day 22, part one (Monkey Market)

Author: rhaendel

src/main/kotlin/de/ronny_h/aoc/year24/day22/MonkeyMarket.kt

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+package de.ronny_h.aoc.year24.day22
+
+import de.ronny_h.aoc.AdventOfCode
+
+fun main() = MonkeyMarket().run(17965282217, 0)
+
+class MonkeyMarket : AdventOfCode<Long>(2024, 22) {
+
+    fun nextSecretNumber(seed: Long): Long {
+        var secret = (seed * 64) xor seed
+        secret %= 16777216
+        secret = (secret / 32) xor secret
+        secret %= 16777216
+        secret = (secret * 2048) xor secret
+        secret %= 16777216
+        return secret
+    }
+
+    override fun part1(input: List<String>): Long = input
+        .map(String::toLong)
+        .sumOf {
+            var secret = it
+            repeat(2000) {
+                secret = nextSecretNumber(secret)
+            }
+            secret
+        }
+
+    override fun part2(input: List<String>): Long {
+        TODO("Not yet implemented")
+    }
+}

src/test/kotlin/de/ronny_h/aoc/year24/day22/MonkeyMarketTest.kt

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+package de.ronny_h.aoc.year24.day22
+
+import de.ronny_h.aoc.extensions.asList
+import io.kotest.core.spec.style.StringSpec
+import io.kotest.matchers.shouldBe
+
+class MonkeyMarketTest : StringSpec({
+
+    val input = """
+        1
+        10
+        100
+        2024
+    """.asList()
+    val market = MonkeyMarket()
+
+    "next secret number of 123" {
+        market.nextSecretNumber(123) shouldBe 15887950
+    }
+
+    "next ten secret numbers of 123" {
+        var secret = 123L
+        buildList {
+            repeat(10) {
+                secret = market.nextSecretNumber(secret)
+                add(secret)
+            }
+        } shouldBe listOf(
+            15887950,
+            16495136,
+            527345,
+            704524,
+            1553684,
+            12683156,
+            11100544,
+            12249484,
+            7753432,
+            5908254,
+        )
+    }
+
+    "part 1" {
+        market.part1(input) shouldBe 37327623
+    }
+})