Leetcode 3293. Calculate Product Final Price

Given an array of product prices and discount rules that depend on other items (e.g., the next cheaper item to the right or discounts valid over ranges), compute each product's final price after applying the applicable discount. The core challenge is to efficiently identify the correct discount for every product across large inputs, commonly solved with monotonic stacks for next‑applicable patterns or with sorting/segment trees for range-based rules.