罗马数字转整数

[Vexth]

func romanToInt(s string) int {
    m := map[rune]int{
      'I': 1,
      'V': 5,
      'X': 10,
      'L': 50,
      'C': 100,
      'D': 500,
      'M': 1000,
    }

    sum, curr, next, i := 0, 0, 0, 0
    for i < len(s) {
        if i == len(s) - 1 {
            sum += m[rune(s[i])]
            break
        }
        curr = m[rune(s[i])]
        next = m[rune(s[i+1])]
        
        if curr < next {
            sum += next - curr
            i += 2 
        } else {
            sum += curr
            i ++
        }
    }

    return sum
}