get solution's source code from web form
get a valid temp file and store solution in it

# Here's my rudimental flocking system
while ( -e "exercise_code.in" ) {}

get from the database exercise_code.in and exercise_code.out
compile solution's source code (using gcc)
run the solution (it will produce executable_filename.out)
File::Compare executable_filename.out and exercise_code.out
if they are the same
        insert solution in the database
else
        wrong answer!