day 23 part 1 working

day23/.gitignore

@@ -0,0 +1,5 @@
+.DS_Store
+/.build
+/Packages
+/*.xcodeproj
+xcuserdata/

day23/Package.swift

@@ -0,0 +1,22 @@
+// swift-tools-version:5.3
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "day23",
+    dependencies: [
+        // Dependencies declare other packages that this package depends on.
+        // .package(url: /* package url */, from: "1.0.0"),
+    ],
+    targets: [
+        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
+        // Targets can depend on other targets in this package, and on products in packages this package depends on.
+        .target(
+            name: "day23",
+            dependencies: []),
+        .testTarget(
+            name: "day23Tests",
+            dependencies: ["day23"]),
+    ]
+)

day23/README.md

@@ -0,0 +1,3 @@
+# day23
+
+A description of this package.

day23/Sources/day23/main.swift

@@ -0,0 +1,66 @@
+
+import Foundation
+
+struct FixedSizeBuffer {
+    var buffer: [Int]
+    private var currentIndex = 0
+
+    init(_ values: [Int]) {
+        buffer = values
+    }
+
+    func getNextThree() -> [Int] {
+        [buffer[(currentIndex + 1) % buffer.count],
+         buffer[(currentIndex + 2) % buffer.count],
+         buffer[(currentIndex + 3) % buffer.count]
+        ]
+    }
+
+    func findNextValue(moving: [Int]) -> Int {
+        var candidate = buffer[currentIndex]
+        repeat {
+            if candidate == 1 {
+                candidate = 9
+            } else {
+                candidate -= 1
+            }
+        } while moving.contains(candidate)
+        return candidate
+    }
+
+    mutating func moveThree() {
+        let moving = getNextThree()
+        let destValue = findNextValue(moving: moving)
+
+        var destIdx = (currentIndex + 1) % buffer.count
+        var srcIdx = (currentIndex + 4) % buffer.count
+        var movedDest = false
+        while !movedDest {
+            buffer[destIdx] = buffer[srcIdx]
+            movedDest = buffer[destIdx] == destValue
+            destIdx = (destIdx + 1) % buffer.count
+            srcIdx = (srcIdx + 1) % buffer.count
+        }
+        for i in 0..<moving.count {
+            buffer[(destIdx + i) % buffer.count] = moving[i]
+        }
+        currentIndex = (currentIndex + 1) % buffer.count
+    }
+
+    func printLabelValues() {
+        let oneIdx = buffer.firstIndex(of: 1)!
+        for i in 1..<buffer.count {
+            print(buffer[(oneIdx + i) % buffer.count], terminator: "")
+        }
+    }
+}
+
+let input = "326519478"
+//let input = "389125467" // test input
+
+var values = FixedSizeBuffer(input.compactMap { Int(String($0)) })
+for _ in 0..<100 {
+    values.moveThree()
+}
+
+values.printLabelValues()

day23/Tests/LinuxMain.swift

@@ -0,0 +1,7 @@
+import XCTest
+
+import day23Tests
+
+var tests = [XCTestCaseEntry]()
+tests += day23Tests.allTests()
+XCTMain(tests)

day23/Tests/day23Tests/XCTestManifests.swift

@@ -0,0 +1,9 @@
+import XCTest
+
+#if !canImport(ObjectiveC)
+public func allTests() -> [XCTestCaseEntry] {
+    return [
+        testCase(day23Tests.allTests),
+    ]
+}
+#endif

day23/Tests/day23Tests/day23Tests.swift

@@ -0,0 +1,47 @@
+import XCTest
+import class Foundation.Bundle
+
+final class day23Tests: XCTestCase {
+    func testExample() throws {
+        // This is an example of a functional test case.
+        // Use XCTAssert and related functions to verify your tests produce the correct
+        // results.
+
+        // Some of the APIs that we use below are available in macOS 10.13 and above.
+        guard #available(macOS 10.13, *) else {
+            return
+        }
+
+        let fooBinary = productsDirectory.appendingPathComponent("day23")
+
+        let process = Process()
+        process.executableURL = fooBinary
+
+        let pipe = Pipe()
+        process.standardOutput = pipe
+
+        try process.run()
+        process.waitUntilExit()
+
+        let data = pipe.fileHandleForReading.readDataToEndOfFile()
+        let output = String(data: data, encoding: .utf8)
+
+        XCTAssertEqual(output, "Hello, world!\n")
+    }
+
+    /// Returns path to the built products directory.
+    var productsDirectory: URL {
+      #if os(macOS)
+        for bundle in Bundle.allBundles where bundle.bundlePath.hasSuffix(".xctest") {
+            return bundle.bundleURL.deletingLastPathComponent()
+        }
+        fatalError("couldn't find the products directory")
+      #else
+        return Bundle.main.bundleURL
+      #endif
+    }
+
+    static var allTests = [
+        ("testExample", testExample),
+    ]
+}