As there are always lots of codes that are copied from ideone, i would suggest codechef to integrate a code editor within the site, just like hacker earth or hacker rank. That would drastically reduce the cheating cases.
No doubt,this is a good idea.It should provide options such as run test cases and then after the user can submit its code for the final.One more thing i would like to add is a wrong answer should show the % of correct answers mathched ,becuase in many problems it happens that we solved the question correctly but it gives wrong answer for minor mistakes like declaring int instead of long long int.
I completely agree with @sandeep9 in this issue. Well i won’tt comment upon awarding partial marks but the procedure could be made similar to SPOJ where we can see the execution on each test file…
partial marking is a different issue