Java Challenge

  void combos(String letters) {
      addAnswer(letters);addAnswer("");
      for(int q=1;q<letters.length();q++) {
          combos(letters.substring(q));
          combos(letters.substring(0,q));
      }
  }

> println("System");

It gives this error: "At line undefined, the submission failed to compile with the error: Error: Sorry, but you may not use the keyword 'System'"

This tool has a list of blacklisted words that can not appear in your source code.

The whole JVM lives in the browser, so you don't need to rely on hacks to "sanitize" user programs.

    \u0052untime r =
    \u0052untime.\u0067\u0065\u0074\u0052untime();
    //println(r.availableProc\u0065ssors() +", " + r.freeMemory());
    //r.exit(1);
    //r.halt(1);