12. Integer to Roman

Roman.swift

/**
 * Question Link: https://leetcode.com/problems/integer-to-roman/
 */
class Solution {
    enum Roman: Int, CaseIterable {
        case I = 1
        case IV = 4
        case V = 5
        case IX = 9
        case X = 10
        case XL = 40
        case L = 50
        case XC = 90
        case C = 100
        case CD = 400
        case D = 500
        case CM = 900
        case M = 1000
    }
    
    func intToRoman(_ num: Int) -> String {
        var num = num
        var result = ""
        var allCases = Roman.allCases
        let allCasesReversed = allCases.reversed()
        for r in allCasesReversed {
            while num % r.rawValue != num && num > 0 {
                result += "\(r)"
                num -= r.rawValue
            }
        }
        return result
    }
}

Solution().intToRoman(3) == "III"
Solution().intToRoman(58) == "LVIII"
Solution().intToRoman(1994) == "MCMXCIV"