day2 done

Author: analogrelay

2021/adventofcode.xcodeproj/project.pbxproj

@@ -10,6 +10,7 @@
 		ABCB126BD61EBC097A1FBD5D /* SimpleError.swift in Sources */ = {isa = PBXBuildFile; fileRef = ABCB163CCB3DF19256E3ADCB /* SimpleError.swift */; };
 		ABCB141AA99DBF03022E6C42 /* day01.swift in Sources */ = {isa = PBXBuildFile; fileRef = ABCB1F5CDAD661579BDFB97A /* day01.swift */; };
 		ABCB1547F4757B4A5384C213 /* Utils.swift in Sources */ = {isa = PBXBuildFile; fileRef = ABCB1F64F82975B897AD4AA6 /* Utils.swift */; };
+		ABCB1A8D8C8C8615FD68B07D /* day02.swift in Sources */ = {isa = PBXBuildFile; fileRef = ABCB14FA942C5989E6DC0A1A /* day02.swift */; };
 		ABCB1C0BA0E8304627F64005 /* main.swift in Sources */ = {isa = PBXBuildFile; fileRef = ABCB1647013E256164F48DBD /* main.swift */; };
 /* End PBXBuildFile section */
 
@@ -27,6 +28,7 @@
 
 /* Begin PBXFileReference section */
 		ABCB12FB57EF41342FB843A5 /* adventofcode */ = {isa = PBXFileReference; explicitFileType = "compiled.mach-o.executable"; includeInIndex = 0; path = adventofcode; sourceTree = BUILT_PRODUCTS_DIR; };
+		ABCB14FA942C5989E6DC0A1A /* day02.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = day02.swift; sourceTree = "<group>"; };
 		ABCB163CCB3DF19256E3ADCB /* SimpleError.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = SimpleError.swift; sourceTree = "<group>"; };
 		ABCB1647013E256164F48DBD /* main.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = main.swift; sourceTree = "<group>"; };
 		ABCB1B9EE9236FD6BA3DE934 /* Makefile */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.make; path = Makefile; sourceTree = "<group>"; };
@@ -60,6 +62,7 @@
 				ABCB1F5CDAD661579BDFB97A /* day01.swift */,
 				ABCB163CCB3DF19256E3ADCB /* SimpleError.swift */,
 				ABCB1F64F82975B897AD4AA6 /* Utils.swift */,
+				ABCB14FA942C5989E6DC0A1A /* day02.swift */,
 			);
 			path = adventofcode;
 			sourceTree = "<group>";
@@ -124,6 +127,7 @@
 				ABCB141AA99DBF03022E6C42 /* day01.swift in Sources */,
 				ABCB126BD61EBC097A1FBD5D /* SimpleError.swift in Sources */,
 				ABCB1547F4757B4A5384C213 /* Utils.swift in Sources */,
+				ABCB1A8D8C8C8615FD68B07D /* day02.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

2021/adventofcode/day02.swift

@@ -0,0 +1,73 @@
+//
+// Created by Andrew Stanton-Nurse on 12/3/21.
+//
+
+import Foundation
+
+struct Coordinate {
+    var depth = 0
+    var position = 0
+}
+
+extension Coordinate {
+    static func +(left: Coordinate, right: Coordinate) -> Coordinate {
+        Coordinate(depth: left.depth + right.depth, position: left.position + right.position)
+    }
+}
+
+class Submarine {
+    var location = Coordinate()
+    var aim = 0
+
+    func move(by: Coordinate) {
+        aim += by.depth
+        location = Coordinate(
+            depth: location.depth + (by.position * aim),
+            position: location.position + by.position)
+    }
+}
+
+func parseInstruction(s: Substring) throws -> Coordinate {
+    let splat = s.split(separator: " ")
+    if splat.count != 2 {
+        throw SimpleError.error("Invalid instruction: \(s))")
+    }
+    guard let count = Int(splat[1]) else {
+        throw SimpleError.error("Distance is not an integer: \(splat[1])")
+    }
+
+    switch splat[0] {
+    case "forward":
+        return Coordinate(depth: 0, position: count)
+    case "down":
+        return Coordinate(depth: count, position: 0)
+    case "up":
+        return Coordinate(depth: -count, position: 0)
+    case let x:
+        throw SimpleError.error("Unknown direction: \(x)")
+    }
+}
+
+func day02(_ args: ArraySlice<String>) throws {
+    guard let input = args.first else {
+        throw SimpleError.error("Usage: adventofcode 2 <input>")
+    }
+    let data = try parseLines(path: input, converter: parseInstruction)
+
+    let part1 = data.reduce(Coordinate(), +)
+    print("Part 1:")
+    dumpResult(result: part1)
+
+    let sub = Submarine()
+    for inst in data {
+        sub.move(by: inst)
+    }
+    print("Part 2")
+    dumpResult(result: sub.location)
+}
+
+func dumpResult(result: Coordinate) {
+    print(" Depth: \(result.depth)")
+    print(" Position: \(result.position)")
+    print(" Result: \(result.position * result.depth)")
+}

2021/adventofcode/main.swift

@@ -8,15 +8,16 @@
 
 import Foundation
 
+let days = [
+    day01,
+    day02
+]
+
 func runDay(number: Int, args: ArraySlice<String>) throws {
-    switch number {
-    case 1:
-        try day01(args);
-        break;
-    default:
-        fputs("Day \(number) not implemented!\n", stderr)
-        exit(1)
+    if number < 1 || number > days.count {
+        throw SimpleError.error("Day not implemented: \(number)")
     }
+    try days[number - 1](args)
 }
 
 if CommandLine.arguments.count < 2 {