Example presention
In this example, we are going to solve a simple challenge about strings. This is Ave Caesar I.
As you can see on the page of the challenge, the ID is 4, we are going to use this piece of information in the code in order to solve it.
This example is aimed at showing how to handle strings with the libraries.
Let's see what the solutions look like in C/C++, Java and Python.
Solution in C/C++
This ID (4) is used at this line :
ErrorCode = MC_StartContest(4, "Your nickname", "Your password");
Solution :
#include "microcontest2.h"
#include <stdio.h>
int main()
{
/************************************************************************/
/*********************VARIABLES DECLARATIONS*****************************/
/************************************************************************/
MC_ResultStruct Res; // Structure that will be filled with the results information
unsigned int ErrorCode;
int LibUpToDate;
char *pCryptedText = NULL; // Variables related to the
unsigned int CryptedTextLength = 0; // contest.
char *pPlainText = NULL;
int Key = 0;
unsigned int c = 0;
/************************************************************************/
/*************CHECKING IF THE LIB MICROCONTEST IS UP TO DATE*************/
/************************************************************************/
ErrorCode = MC_CheckLibVersion(&LibUpToDate); // Check if the lib microcontest is up to date
if(ErrorCode != MC_OK)
{
MC_ErrorMessage(ErrorCode, 1); // This function prints the message of the error.
return 0;
}
else if(LibUpToDate == 0)
{
printf("Warning: the version of the libmicrocontest2 is not the last one.\n");
printf("Current version:\t%s\n", MC_LIBVERSION);
printf("This program may not work properly. Consider downloading the latest version on\nthis page : http://www.microcontest.com/download.php\n\n");
}
/************************************************************************/
/*****CONNECTING TO THE CHALLENGE AND GETTING THE VARIABLES VALUES*******/
/************************************************************************/
ErrorCode = MC_StartContest(4, "Your nickname", "Your password"); // Call this function to make the library get the variables values of a challenge.
if(ErrorCode != MC_OK)
{
MC_ErrorMessage(ErrorCode, 1);
return 0;
}
ErrorCode = MC_GetParam_char("txt_crypte", &pCryptedText, &CryptedTextLength); // Get the variables values. Depending on the contest, you can get int,
ErrorCode *= MC_GetParam_int("key", &Key); // float, or string values thanks to the functions MC_GetParam_xxx.
if(ErrorCode == 0)
{
printf("Impossible to get the contest data. Please check the ID of the contest.\n");
return 0;
}
/************************************************************************/
/*********************SOLVING THE CHALLENGE******************************/
/************************************************************************/
pPlainText = (char *)malloc((CryptedTextLength + 1)*sizeof(char)); // Solve the contest itself here
if(pPlainText == NULL)
{
printf("Error, impossible to allocate the memory for pPlainText\n");
return 0;
}
else
pPlainText[CryptedTextLength] = 0;
for(c = 0; c < CryptedTextLength; c++)
{
pPlainText[c] = pCryptedText[c] - Key;
if(pPlainText[c] < 65)
pPlainText[c] += 26;
}
printf("Crypted text :\t%s\n", pCryptedText);
printf("Key :\t\t%d\n", Key);
printf("Plain text:\t%s\n\n", pPlainText);
/************************************************************************/
/*SENDING THE SOLUTION TO THE SERVER AND PRINTING THE RESULT INFORMATION*/
/************************************************************************/
MC_AddVariableToSolution_char("txt_clair", pPlainText, strlen(pPlainText)); // Add the variable to the solution. You can add several depending on
// the contest
free(pPlainText);
ErrorCode = MC_SendSolution(&Res); // Send the solution to the server
if(ErrorCode != MC_OK)
MC_ErrorMessage(ErrorCode, 1);
MC_ResultMessage(&Res, 1); // This function prints a summary of the results
return 0;
}
download source file (copy/paste adds special characters)
Solution in Python
This ID (4) is used at this line :
cont = commence_contest(4, "Your nickname", "Your password")
Solution :
# -*- coding: utf-8 -*-
from libmicrocontest2_python27 import *
if not check_version():
print "Warning: the version of the libmicrocontest2 is not the last one."
print "Current version :\t" + get_currentversion()
print "This program may not work properly. Consider downloading the latest version on\nthis page : http://www.microcontest.com/download.php\n"
cont = commence_contest(4, "Your nickname", "Your password")
# short form uses username, password from credentials.py
# cont = commence_contest(1)
CryptedText = cont.get_str('txt_crypte')
Key = cont.get_int('key')
PlainText = ''
for c in CryptedText:
NewChar = ord(c) - Key
if NewChar < 65:
NewChar += 26
PlainText += chr(NewChar)
print 'CryptedText:\t' + CryptedText
print 'Key:\t\t' + str(Key)
print 'PlainText:\t' + PlainText
cont.append_answer("txt_clair", PlainText)
print(cont.submit_answer())
download source file (copy/paste adds special characters)
Solution in Java
This ID (4) is used at this line :
Contest cont = Contest.commenceContest(4, "Your nickname", "Your password");
Solution :
import com.microcontest.Libmicrocontest2;
import com.microcontest.Contest;
public class Contest4 {
public static void main(String[] args) {
if(Libmicrocontest2.checkVersion() == false)
{
System.out.println("Warning: the version of the libmicrocontest2 is not the last one.");
System.out.println("Current version :\t" + Libmicrocontest2.VERSION);
System.out.println("This program may not work properly. Consider downloading the latest version on this page : http://www.microcontest.com/download.php\n");
}
Contest cont = Contest.commenceContest(4, "Your nickname", "Your password");
// Contest cont = Contest.commenceContest(4); if you use credentials
int key = cont.getInt("key");
String txt_crypted = cont.getParam("txt_crypte");
char[] txt_plain = new char[txt_crypted.length()];
for(int c = 0; c < txt_crypted.length(); c++)
{
txt_plain[c] = (char)(txt_crypted.charAt(c) - key);
if(txt_plain[c] < 65)
txt_plain[c] += 26;
}
System.out.println("Crypted text :\t" + txt_crypted);
System.out.println("Key :\t\t" + key);
System.out.println("Plain text :\t" + String.valueOf(txt_plain));
cont.appendAnswer("txt_clair", String.valueOf(txt_plain));
System.out.println(cont.submitAnswer());
}
}
download source file (copy/paste adds special characters)
Solution in PHP
This ID (4) is used at this line :
$contest->startContest(4, 'Your nickname', 'Your password');
Solution :
<?php
// We include the µContest library
require 'libmicrocontest2.php';
$contest = new uContest();
// We check if the µContest library is up to date
if($contest->checkVersion() == 0)
{
echo 'Warning: the version of the libmicrocontest2 is not the last one.<br />';
echo 'Current version : ' . $contest->version . '<br />';
echo 'This program may not work properly. Consider downloading the latest version on this page : http://www.microcontest.com/download.php<br /><br />';
}
// We connect to the challenge
try {
$contest->startContest(4, 'Your nickname', 'Your password');
} catch (Exception $ex) { echo $ex->getMessage(); exit(); }
// We get the variables of the challenge
$key = intval($contest->getParam('key'));
$cryptedText = $contest->getParam('txt_crypte');
// We solve the challenge itself
$plainText = '';
foreach(str_split($cryptedText) as $c)
{
$newChar = ord($c) - $key;
if($newChar < 65)
$newChar += 26;
$plainText .= chr($newChar);
}
echo "key = $key<br />";
echo "cryptedText = $cryptedText<br />";
echo "plainText = $plainText<br /><br />";
// We add the answer to the answer to be sent. You can add several answers, depending on the challenge
$contest->appendAnswer('txt_clair', $plainText);
// We send the answer(s) and print the result
try {
$result = $contest->sendAnswer();
} catch (Exception $ex) { echo $ex->getMessage(); exit(); }
print_r($result);
?>
download source file (copy/paste adds special characters)
Remove the '_' at the end of the file name
Solution in any other language
Of course, it is possible to solve the challenges in any other language. But for that, you must develop your own functions of communication with the webiste.
You can take a look at the source code of our libraries to help yourself.
The mecanisms of communication are described on the page Interface.
