It would be a good idea to add tutorial link in contest page.

what does the function root() in problem C solution

C's time limit was stupidly strict. 36551515 is TLE(runs in about 2.15 seconds), while 36625920 is AC. The only difference was adding special cases if the exponent>=30.

In problem C, my question is when there are much more element need to be inserted in a container so "should we prefer vector on the place of the set?" in c++.

because of the same thing I implemented using set giving TLE and by vector AC

Can anyone please tell me why are we disposing sqrts in problem c

Problem D can be solved by KMP with O(n) time complexity.

question C can be easily solved by using the Mobius function (inclusion-exclusion of numbers l<=x<=r that can be generated in several ways). However, this solution requiers accuracy of the pow function and in test 5 (very big numbers) I get an off-by-one solution. How can one use the pow function to get the actual floor of the result even if the base is 10^18?

GreenGrape. In question 955C, how do u take care of the repetitions like 1000^2,100^3 which are basically 1000000, but show up in both squares and cubes. Thank you.

By saying 'Let f3(u) will be minimal k, such that heapk(u) is equal to 3.', I guess you actually mean to say 'maximum k'?