Hello everyone, with the help of you guys and helpful blogs, I am able to solve A and B pretty much every time, and most of the time C too(Div >=2 of course).
Here is the problem->Contest #576 Div2 C-MP3
And here is my code->here
For those of you who don't want to see code, here is what I did
-made vector of distinct intensities(which is sorted)
-maintained a freq map for frequency of those intensities
-while the condition of the bits is not satisfied, greedily removed the digits from left and right using two pointers