leetcode-go/medium/592.fraction-addition-and-subtraction.go

type pair struct {
	_1 int
	_2 int
}

func (p1 *pair) add(p2 pair) {
	if p1._1 == 0 {
		*p1 = p2
	} else {
		p1._1 = p1._1*p2._2 + p2._1*p1._2
		p1._2 *= p2._2
	}
}

func fractionAddition(expression string) string {
	beg, end, n := 0, 1, len(expression)
	var sum pair
	for end < n {
		for end = beg + 1; end < n && expression[end] != '+' && expression[end] != '-'; end++ {
		}
		p := str2frac(expression[beg:end])
		sum.add(p)
		beg = end
	}
	i := gcd(abs(sum._1), sum._2)
	return fmt.Sprintf("%d/%d", sum._1/i, sum._2/i)
}

func gcd(a, b int) int {
	if b == 0 {
		return a
	}
	return gcd(b, a%b)
}

func str2frac(s string) (p pair) {
	strs := strings.Split(s, "/")
	p._1, _ = strconv.Atoi(strs[0])
	p._2, _ = strconv.Atoi(strs[1])
	return
}

func abs(x int) int {
	if x < 0 {
		return -x
	}
	return x
}