As I participate in the Educational Codeforces Round 161 (Rated for Div. 2) where i solved 3 out of 6 and I have not use the online resource as ideone as mention in the below post , I usually test my codes on online compiler when i submit the codes on codeforces to check that whether the solution that I have written is workin or not and after checking all the testcases I submit the codes on codeforces contest. In case you found is the solution is matching as something or someone has used my code i don't know about I write my codes privately and don't share with anyone.

"Your solution 241792342 for the problem 1921D significantly coincides with solutions ragnarokx007/241791615, techsinu/241792342, varuagrathore/241793493, Rakk_ss/241794469, mohanlucky460/241798402. Such a coincidence is a clear rules violation. Note that unintentional leakage is also a violation. For example, do not use ideone.com with the default settings (public access to your code). If you have conclusive evidence that a coincidence has occurred due to the use of a common source published before the competition, write a comment to post about the round with all the details. More information can be found at http://codeforces.me/blog/entry/8790. Such violation of the rules may be the reason for blocking your account or other penalties. In case of repeated violations, your account may be blocked."