ACM ICPC World Finals 2012
This was one of the easiest problems. The volume up to point x is simply
V (x) = ∫t= xlowx P( x )dx = ∑i =0n ai/(i + 1) · (xi+1 − xlow)i+1,
and to find the value of x for which V ( x ) is some multiple of inc one can just binary search.