func fractionToDecimal(numerator int, denominator int) string {
    if numerator == 0 {
        return "0"
    }
    ans := []byte{}
    if (numerator > 0) != (denominator > 0) {
        ans = append(ans, '-')
    }
    num := abs(numerator)
    den := abs(denominator)
    ans = append(ans, toByte(num / den)...)
    rem := num % den
    if rem == 0 {
        return string(ans)
    }
    ans = append(ans, '.')
    d := make(map[int]int)
    for rem != 0 {
        if index, exists := d[rem]; exists {
            ans = append(ans[:index+1], ans[index:]...)
            ans[index] = '('
            ans = append(ans, ')')
            break
        }
        d[rem] = len(ans)
        rem *= 10
        ans = append(ans, toByte(rem / den)...)
        rem %= den
    }
    return string(ans)
}

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

func toByte(x int) []byte {
    return []byte(fmt.Sprintf("%v", x))
}

func strStr(haystack string, needle string) int {
    for i := 0; ; i++ {
        for j := 0; ; j++ {
            if j == len(needle) { return i }
            if (i + j == len(haystack)) { return -1 }
            if needle[j] != haystack[i + j] { break }
        }
    }
    return -1
}