The grocery store is having a store-wide sale: buy n items, get 1 item free. The free item must be of equal or lesser value than each of the n items. Fortunately, the store checkout will always find the best deal for the shopper. No matter what order the items are purchased in, it will always choose the highest-priced free item(s) that meet the criteria.
Write a function that calculates the total paid by the shopper, given the number of items to buy before getting 1 free, and a vector giving the price of each item purchased.
For example, if n = 4, and prices = [4.49 4.49 5.19 4.79 4.79], then total = 19.26, since the qualifying free item must be one of the items priced at $4.49.
If n = 2, and prices = [1 2 3 4 5 6 7], then total = 21. Buying the items priced $6 and $7 gets you the item priced $5 for free, and buying the items priced $3 and $4 gets you the item priced $2 for free. The item priced $1 is not part of any deal.
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Last Solution submitted on Nov 03, 2026

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William George Berken goc3 Christian Schröder

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