Kotlin Solution

fun timeConversion(s: String): String {
    val splitString = s.split(":").toMutableList()
    val obtainFormat = splitString.last().takeLast(2)
     val hour = splitString.first().toInt()
    if(obtainFormat == "AM"){
        splitString[0] = String.format("%02d",hour.toInt() % 12)
    } else {
        splitString[0] = String.format("%02d",if(hour < 12) hour + 12 else hour)
    }
    return splitString.joinToString(":").dropLast(2)
}

!/bin/python3

import math import os import random import re import sys

#

Complete the 'timeConversion' function below.

#

The function is expected to return a STRING.

The function accepts STRING s as parameter.

#

def timeConversion(s): # Write your code here period=s[-2:] hours,minutes,seconds=map(int,s[:-2].split(':')) if period=='AM' and hours==12: hours=0 elif period=='PM' and hours !=12: hours+=12 return f"{hours:02}:{minutes:02}:{seconds:02}"

if name == 'main': fptr = open(os.environ['OUTPUT_PATH'], 'w')

s = input()

result = timeConversion(s)

fptr.write(result + '\n')

fptr.close()

public static String timeConversion(String s) {
// Write your code here
    String hours = s.substring(0,2) ;
    String restOfTime = s.substring(2,8);
    String meridian = s.substring(8);

    if((meridian.equals("PM")) && !hours.equals("12")){
        hours = String.valueOf(Integer.parseInt(hours)+12) ;
        }else if(meridian.equals("AM") && hours.equals("12")){
            hours="00";
        }

    return hours + restOfTime;
}

c++20 (chose readability over latency)

string timeConversion(string s) {

int nDigits = 2;

auto time = s.substr(0, s.size() - nDigits);
auto zone = s.substr(s.size() - nDigits);
int hour = stoi(time.substr(0, nDigits));

std::stringstream ss;
ss << std::setw(nDigits) << std::setfill('0');
    
if(zone == "AM"){
    auto amHour = hour%12;

    ss << amHour << time.substr(nDigits);
}
else{
    
    auto pmHour = hour;
    
    if(hour < 12){
        pmHour = hour + 12;
    }

    ss << pmHour << time.substr(nDigits);
}

return ss.str();
}

def timeConversion(s): period = s[-2:] #last two digits = pm/am time = s[:-2] #without last two digits = time hms = list(map(int, time.split(':'))) #splits the list and converts str into int in one line

if period == 'AM':
    if hms[0] == 12:
        hms[0] -= 12
if period == 'PM':
    if not hms[0] == 12:
        hms[0] += 12

hms = [f"{i:02}" for i in hms] #makes sure only two digits allowed
return ":".join(hms) #reproducing string