Java :

public static String timeConversion(String s) {

    String ampm = s.substring(8, 10);
    int hrs = Integer.parseInt(s.substring(0, 2));
    String str="";
    if(ampm.equalsIgnoreCase("PM"))
    {
        if(hrs!=12)
        {
            hrs+=12;
        }
        str = String.valueOf(hrs)+s.substring(2, 8);
    }
    else{
        if(hrs==12)
        {
            str = "00"+s.substring(2, 8);
        }
        else if(hrs<10)
        {
            str = "0"+String.valueOf(hrs)+s.substring(2, 8);
        }
    }
    return str;

}

This is my solution:

def timeConversion(s):
    # Write your code here 
    if s.rfind("PM") == 8 and s.split(":")[0] != "12":
        s = s.strip("PM").replace(s.split(":")[0],str(int(s.split(":")[0])+12))
        
    elif s.rfind("AM") == 8 and s.split(":")[0] == "12":
        s = s.strip("AM").replace("12","00")
        
    else:
        s = s.strip("AM").strip("PM")
    return s

Had some fun with this one JS Let me know how I can imporve!!

function timeConversion(s) {
    // Write your code here
    let hrs = s.slice(0,2)
    let min = s.slice(3,5)
    let sec = s.slice(6,8)
    let amPm = s.slice(8,10)
    
   if( amPm === 'PM'){
       hrs = parseInt(hrs)
       if(hrs < 12){
           hrs = hrs + 12
       }
   } else if (amPm === "AM"){
       if (hrs === '12'){
           hrs = '00'
       }
   }
   return `${hrs}:${min}:${sec}`
}

This is my solution using JavaScript

function timeConversion(s) {
  //Variables to hold the individual time pieces
  let hrs = s.slice(0,2);
  const mins = s.slice(3,5);
  const sec = s.slice(6,8);

  //Conditional to determine the time conversion
  if (s.includes("AM")) {
    if (hrs === '12') {
      hrs = '00';
    }
    return `${hrs}:${mins}:${sec}`;
  } else {
    hrs = parseInt(hrs);
    if (hrs < 12) {
      hrs = hrs + 12;
    }
    return `${hrs}:${mins}:${sec}`;
  }
	
}

public static String timeConversion(String s) { // Write your code here String output = ""; String newhour = ""; String[] parts = s.split(":|(?=[AP]M)"); String hour = parts[0]; String minute = parts[1]; String second = parts[2].substring(0, 2); String ampm = parts[2].substring(2);

    if(ampm.equals("AM")){
        if(hour.equals("12")){
            newhour = "00";
        }
        else{
            newhour = hour;
        }
        output = newhour+":"+minute+":"+second;
    }else{
        if(!hour.equals("12")){
            int hournumber = Integer.parseInt(hour);
            hournumber = hournumber+12;
            newhour = Integer.toString(hournumber);  
        }
        else{
            newhour=hour;
        }
        output = newhour+":"+minute+":"+second;
    } 
    return output;
}

what is wrong with this solution ?