66 lines
1.9 KiB
Swift
66 lines
1.9 KiB
Swift
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import Foundation
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let input = loadData(day: 12)
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let scanner = Scanner(string: input)
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var position = (north: 0, east: 0)
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var waypoint = (north: 1, east: 10)
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var direction = 0
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/*
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while !scanner.isAtEnd {
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guard let instruction = scanner.scanCharacter(), let value = scanner.scanInt() else {
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fatalError("Invalid input")
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}
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switch instruction {
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case "N": position.north += value
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case "S": position.north -= value
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case "E": position.east += value
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case "W": position.east -= value
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case "L": direction = (360 + direction - value) % 360
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case "R": direction = (direction + value) % 360
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case "F":
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switch direction {
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case 0: position.east += value
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case 90: position.north -= value
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case 180: position.east -= value
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case 270: position.north += value
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default: fatalError("Invalid direction")
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}
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default: fatalError("Invalid command")
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}
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}
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*/
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func turn(_ degrees: Int) -> (north: Int, east: Int) {
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switch degrees {
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case 0: return waypoint
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case 90: return (-waypoint.east, waypoint.north)
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case 180: return (-waypoint.north, -waypoint.east)
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case 270: return (waypoint.east, -waypoint.north)
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default: fatalError("Invalid direction")
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}
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}
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while !scanner.isAtEnd {
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guard let instruction = scanner.scanCharacter(), let value = scanner.scanInt() else {
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fatalError("Invalid input")
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}
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switch instruction {
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case "N": waypoint.north += value
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case "S": waypoint.north -= value
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case "E": waypoint.east += value
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case "W": waypoint.east -= value
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case "R": waypoint = turn(value)
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case "L": waypoint = turn(360 - value)
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case "F":
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position.north += value * waypoint.north
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position.east += value * waypoint.east
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default: fatalError("Invalid command")
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}
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}
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print(abs(position.north) + abs(position.east))
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