hackerrank Time Conversion problem solution in Golang

hackerrank_time_conversion_solution.go

/*
 * Complete the 'timeConversion' function below.
 *
 * The function is expected to return a STRING.
 * The function accepts STRING s as parameter.
 */
func timeConversion(s string) string {
    var AM_PM string = s[len(s)-2:]
    
    // split time strings
    tt := strings.Split(s[:len(s)-2], ":")
    
    // convert hour to int
    h, err := strconv.Atoi(tt[0])
    if err != nil {
        panic(err)
    }
    
    // if before noon minus 12 from hour else add 12 to hour
    if AM_PM == "AM" {
        if h == 12 {
            h = 0
        }
    } else {
        if h != 12 {
            h += 12   
        }
    }
    
    return fmt.Sprintf("%02d:%s:%s", h, tt[1], tt[2])
}