I have solved FCTRE of this long challenge using mo’s algorithm. where one of the correct solution gave TLE.
After the contest, I re-submitted the code with blocksize 630 and it gave AC with 3.29s Here
It could have been okay if It got TLE within 1s range. but here is the difference of around 4s.
This would be dangerous for short contests.
(Side note : I believe that for a certain block size, we should get minimum time and by either increasing or decreasing the block size, it would increase the running time, am I correct or not ?)