import scala.util.Random
/*
Select N unique random indices from an existing array in Scala.
Return the indices and print both the index and the corresponding value.
Approach:
- Build a sequence of indices: 0, 1, 2, ..., size-1.
- Shuffle the indices using Random.shuffle (Fisher–Yates internally).
- Take the first N shuffled indices — guaranteed unique.
- Return those indices to the caller.
*/
// Return N unique random indices
def pickUniqueIndices(arraySize: Int, count: Int): Seq[Int] = {
if (count > arraySize)
throw new IllegalArgumentException("Cannot pick more unique indices than array size.")
// Build index list
val indices: Seq[Int] = 0 until arraySize
// Shuffle and take first N
Random.shuffle(indices).take(count)
}
@main def main(): Unit = {
// Example array
val data: Array[Int] = Array(5, 12, 5, 19, 5, 33, 47, 5, 58, 61, 17, 3, 5, 74, 83, 90, 6)
val N: Int = 6 // number of unique indices to pick
// Get unique random indices
val indices: Seq[Int] = pickUniqueIndices(data.length, N)
// Print results
println("Random unique indices and their values:")
indices.foreach { idx =>
println(s"index $idx -> value ${data(idx)}")
}
}
/*
run:
Random unique indices and their values:
index 5 -> value 33
index 4 -> value 5
index 0 -> value 5
index 3 -> value 19
index 11 -> value 3
index 14 -> value 83
*/
