day 1 part 1

day01/.gitignore

@@ -0,0 +1,8 @@
+.DS_Store
+/.build
+/Packages
+xcuserdata/
+DerivedData/
+.swiftpm/configuration/registries.json
+.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
+.netrc

day01/Package.swift

@@ -0,0 +1,15 @@
+// swift-tools-version: 6.2
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "day01",
+    targets: [
+        // Targets are the basic building blocks of a package, defining a module or a test suite.
+        // Targets can depend on other targets in this package and products from dependencies.
+        .executableTarget(
+            name: "day01"
+        ),
+    ]
+)

day01/Sources/day01/day01.swift

@@ -0,0 +1,47 @@
+// The Swift Programming Language
+// https://docs.swift.org/swift-book
+
+@main
+struct day01 {
+    static func parseInput(_ input: String) -> [(Direction, Int)] {
+        return input.split(whereSeparator: \.isNewline)
+            .map({ line in
+                return (Direction(line.first!), Int(line.dropFirst())!)
+            })
+
+    }
+
+    static func part1(_ input: [(Direction, Int)]) {
+        var cur = 50
+        var count = 0
+        for (dir, num) in input {
+            let last = cur
+            cur = switch dir {
+                case .Left: (cur - num) % 100
+                case .Right: (cur + num) % 100
+            }
+            if (cur < 0) { cur += 100 }
+            print(last, cur, dir, num)
+            if (cur == 0) { count += 1 }
+        }
+        print("Part 1: \(count)")
+    }
+
+    static func main() {
+        let parsed = parseInput(realInput)
+        part1(parsed)
+    }
+}
+
+enum Direction {
+    case Left
+    case Right
+
+    init(_ char: Character) {
+        self = switch char {
+            case "L": Direction.Left
+            case "R": Direction.Right
+            default: fatalError()
+        }
+    }
+}