LESSON 193 OF 414 · NESTED LOOPS

Top K Brands V4 - Top K in Scala

Practice

Show the top k brands by rating. This is v3's search, repeated k times: find the best brand, mark it as taken, then search again among the brands that are not taken yet, until you have k brands in rank order.

You start with:

        val brands = Array("TechPro", "MegaCorp", "Quantum", "NeoByte", "Zenith")
        val ratings = Array(4, 5, 3, 5, 4)
        val k = 3

Build:

1. MegaCorp (5)
2. NeoByte (5)
3. TechPro (4)

Rules:

Repeat v3's search k times. Each round looks only at brands that are not taken yet and picks the one with the highest rating, then marks it as taken (one true/false flag per brand).
Ties go to the brand listed first: keep the first brand you find and replace it only on a strictly higher rating.
k is never larger than the number of brands.
Each line is "rank. Brand (rating)", starting at rank 1.
Print the lines, one per line, with println(...).

Start with the two declarations val used = Array.fill(ratings.size)(false) and val lines = scala.collection.mutable.ArrayBuffer[String](). A flag tells whether that position is already taken.

Each round is v3's search: nothing found yet, scan every position, skip taken ones, keep the first candidate and replace it only on a strictly higher rating. Then mark the winner as taken and add its line.

        val brands = Array("TechPro", "MegaCorp", "Quantum", "NeoByte", "Zenith")
        val ratings = Array(4, 5, 3, 5, 4)
        val k = 3

        val used = Array.fill(ratings.size)(false)
        val lines = scala.collection.mutable.ArrayBuffer[String]()
        for (rank <- 1 to k) {
            var bestIndex = -1
            for (i <- ratings.indices) {
                if (!used(i)) {
                    if (bestIndex == -1 || ratings(i) > ratings(bestIndex)) {
                        bestIndex = i
                    }
                }
            }
            used(bestIndex) = true
            lines.append(s"$rank. ${brands(bestIndex)} (${ratings(bestIndex)})")
        }
        println(lines.mkString("\n"))

STEP 1 OF 11

Guided

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Top K Brands V4 - Top K in Scala

Top K Brands V4 in Scala