12th December solution - Advent of Code 2020 - swift

december12_1.swift

var x = 0.0
var y = 0.0
var direction = 0.0 // degrees east

lines.forEach { (line) in
    if let instruction = line.first, let amount = Double(line.dropFirst()) {
        if instruction == "E" {
            x += amount
        } else if instruction == "W" {
            x -= amount
        } else if instruction == "N" {
            y -= amount
        } else if instruction == "S" {
            y += amount
        } else if instruction == "F" {
            x += amount * __cospi(direction/180.0)
            y += amount * __sinpi(direction/180.0)
        } else if instruction == "R" {
            direction += amount
        } else if instruction == "L" {
            direction -= amount
        }
    }
}

print(abs(x) + abs(y))

december12_2.swift

var waypointX = 10.0
var waypointY = -1.0
var x = 0.0
var y = 0.0

lines.forEach { (line) in
    if let instruction = line.first, let amount = Double(line.dropFirst()) {
        if instruction == "E" {
            waypointX += amount
        } else if instruction == "W" {
            waypointX -= amount
        } else if instruction == "N" {
            waypointY -= amount
        } else if instruction == "S" {
            waypointY += amount
        } else if instruction == "F" {
            x += amount * waypointX
            y += amount * waypointY
        } else if instruction == "R" {
            for _ in 0 ..< Int(amount/90) {
                let oldX = waypointX
                let oldY = waypointY
                waypointX = oldY * -1
                waypointY = oldX
            }
        } else if instruction == "L" {
            for _ in 0 ..< Int(amount/90) {
                let oldX = waypointX
                let oldY = waypointY
                waypointX = oldY
                waypointY = oldX * -1
            }
        }
    }
}
print(abs(x) + abs(y))

december12_shared.swift

let filename = "/Users/felix/xCodeProjects/AdventOfCode2020.playground/Resources/december12.txt"
let contents = try! String(contentsOfFile: filename)
var lines = contents.components(separatedBy: CharacterSet.newlines).filter { !$0.isEmpty }