Can anybody give me hints for this problem from Algorithm Design: Let A be an array of n numbers a_1, a_2, \cdots, a_n. Output an array of n numbers b_1, \cdots, b_n in O(n \; \log n) time such that for all i, we have

b_i = \sum_{0 \leq j \leq n, i \neq j} \frac{a_j}{(j-i)^2}

Can you plz provide the link of the problem? I wanna try this…

@vivek_1998299 It’s an textbook exercise, not from an on-line site. I’ve copied the problem almost verbatim here (without the story)

Is the problem in the upcoming long contest ordered by difficulty ? Since I know only extremely elementary DP/graph theory, how many problems should I target ?

Reading all the questions is actually a good habit @lemonstudy . No, trust me, sometimes the "supposed to be’ harder question turns out to be easier.