Leetcode 3525. Find X Value of Array II

After applying the persistent point update and removing the first start elements for that query, count how many nonempty prefixes of the remaining subarray (i.e., choices of suffix to remove) have product ≡ x (mod k). The core challenge is maintaining and querying multiplicative prefix products under point updates when k may be composite (so modular inverses don't always exist), requiring number‑theoretic/segment‑tree techniques to track residues.