[LeedCode] 13. Roman to Integer (Swift)

https://leetcode.com/problems/roman-to-integer/

로마숫자를 정수로 변환하는 문제

class Solution {
    let integer: [Character: Int] = [
        "I" :1,
        "V" :5,
        "X" :10,
        "L" :50,
        "C" :100,
        "D" :500,
        "M" :1000
    ]

    func romanToInt(_ s: String) -> Int {
        var result = 0
        var previous = 0
        for roman in s.reversed() {
            let digit = integer[roman]!
            if digit >= previous {
                result += digit
            } else {
                result -= digit
            }
            previous = digit
        }
        return result
    }
}