my java solution: ` s= s.trim(); String timeMarker=s.substring(8); String originalTime = s.substring(0, 8); String[] originalTimeList= originalTime.split(":"); String hour = originalTimeList[0]; Integer hourInt = Integer.parseInt(hour); StringBuilder newTime = new StringBuilder();

if(timeMarker.equals("PM")){
    if(hourInt!=12){
        hourInt+=12;
        hour= String.valueOf(hourInt);
    }
}
else{
    if(hourInt==12){
        hour= "00";
    }
}

return newTime.append(String.valueOf(hour)).append(":")
.append(originalTimeList[1]).append(":")
.append(originalTimeList[2]).toString();

`