from roman to numeric.swift

enum Roman: String {
	case M, D, C, L, X, V, I
	
	init(_ v: String) {
		self.init(rawValue: v)!
	}
}

extension Roman {
	var int: Int {
		switch self {
		case .M:
			return 1000
		case .D:
			return 500
		case .C:
			return 100
		case .L:
			return 50
		case .X:
			return 10
		case .V:
			return 5
		case .I:
			return 1
		}
	}
}

extension Array where Element == Roman {
	func toArab(_ i: Int = 0, acc: Int = 0) -> Int {
		guard i < self.count - 1 else {
			return acc + self[i].int
		}
				
		let current = self[i].int
		let next = self[i + 1].int
		
		return current < next
		? toArab(i + 1, acc: acc - current)
		: toArab(i + 1, acc: acc + current)
	}
}


let toArabResult = "MCMXC".map { Roman(String($0)) }.toArab()


print(toArabResult)