Question 1: Item Pricing with Minimum Previous Discount

Problem Statement

You are given a list of item prices at a market. The store has a special discount rule: The first item is purchased at full price. For every subsequent item, the discount applied is equal to the lowest price among all previously purchased items. The final price of an item cannot go below 0. Items must be purchased in the given order. Your task is to calculate the total cost of buying all items under this pricing rule. Example 1 Suppose there are n = 4 prices: prices = [2, 5, 1, 4]. Output: 8 First item costs 2 (no discount applies to the first item) Second item costs 5 - 2 = 3 (minimum previous price was 2) Third item costs max(1 - min(2, 5), 0) = max(1 - 2, 0) = 0 Fourth item costs 4 - 1 = 3 (minimum previous price was 1) Total cost: 2 + 3 + 0 + 3 = 8 Example 2 Suppose n = 4, and prices = [4, 9, 2, 3] Output: 10 First item costs 4 (no discount applies to the first item) Second item costs 9 - 4 = 5 (minimum previous price was 4) Third item costs max(2 - min(4, 9), 0) = max(2 - 4, 0) =