During Yesterday's EDU round, My solution to D was accepted and during system testing, it got TLE on test case 60. AC during contest : (https://mirror.codeforces.com/contest/1499/submission/110354551)

Now I submitted the same code multiple times after system testing is over, it is getting accepted. AC after system testing : https://mirror.codeforces.com/contest/1499/submission/110419651

So can anyone please tell what can be wrong in this scenario ?