Today while hacking(Codeforces Round #555: Div 3) I came across the following solutions by 4ul_sharma and utkarshv3 who are from the same institute.

Problem B: Was there an actual need of sieve in 53330133 by 4ul_sharma ? 's1[s[i] — 48]' and val[s[i] — '0'] is the only difference in both solutions. 53329059 is by utkarshv3.

Problem C1: Similiar solution once again. 53339717 is by 4ul_sharma and has been hacked. 53337439 is by utkarshv3 (Expecting it to get hacked too) and you can observe the same pattern except change of variables and printing 'L' corresponding to 1 and 'R' corresponding to 0 in 4ul_sharma's solution.

Problem C2: 53354481 is by 4ul_sharma, 53356166 is by utkarshv3. Exactly similiar code, just change of variables. Again playing with 1 and 0 to print 'L' and 'R'.

Problem D: 53364711 is by 4ul_sharma, 53364674 is by utkarshv3. Again a similiar code but change of variables.

Problem E: 53342437 is by 4ul_sharma, 53343985 is by utkarshv3. And once again a similiar code with a few change of variables.

The culprits involved are from the same college/organisation(JIIT Noida) : 4ul_sharma and utkarshv3.

And you can notice the time of their submissions.

In such cases of cheating, what should be done? This is happening over and over again on this platform. MikeMirzayanov and vovuh please look into it.