package q13

func lookup(b byte) int {
	switch b {
	case 'I':
		return 1
	case 'V':
		return 5
	case 'X':
		return 10
	case 'L':
		return 50
	case 'C':
		return 100
	case 'D':
		return 500
	case 'M':
		return 1000
	}
	return 0
}

func romanToInt(s string) int {
	num := 0
	prev := 0
	for i := range len(s) {
		cur := lookup(s[i])
		num += cur
		if prev < cur {
			num -= prev + prev
		}
		prev = cur
	}
	return num
}

var _ = romanToInt