d22p1

day22/d22p1.swift

@@ -0,0 +1,18 @@
+import Foundation
+
+func readInput(_ filePath: String) throws -> [Int] {
+    return try String(contentsOfFile: filePath, encoding: .ascii)
+        .split(separator: "\n").compactMap { Int($0) }
+}
+
+func rand(seed: Int, n: Int) -> Int {
+    return (0..<n).reduce(seed) { prev, _ in
+        var res = ((prev << 6) ^ prev) & 0b111111111111111111111111
+        res = ((res >> 5) ^ res)
+        return ((res << 11) ^ res) & 0b111111111111111111111111
+    }
+}
+
+let seeds = try readInput(CommandLine.arguments[1])
+print(seeds.map { rand(seed: $0, n: 2000) }.reduce(0, +))
+

day22/test.txt

@@ -0,0 +1,4 @@
+1
+10
+100
+2024