// ------------------------------------------------------------
// A small program demonstrating how to remove every Nth element
// from a List<T> using clear, expressive Kotlin patterns.
// ------------------------------------------------------------
/*
removeEveryNth returns a new List<T> with every Nth element removed.
Kotlin lists use zero‑based indexing, so we check (index + 1) % n != 0
to keep elements that are *not* in the Nth position.
The variable "size" captures the list length before the loop,
which avoids repeatedly accessing items.size inside the loop.
A mutable list is used internally for efficient building,
and then converted back to an immutable List at the end.
*/
fun <T> removeEveryNth(items: List<T>, n: Int): List<T> {
require(n > 0) { "n must be a positive integer" }
val size: Int = items.size // capture size once
val result: MutableList<T> = ArrayList(size)
for (i: Int in 0 until size) {
if ((i + 1) % n != 0) {
result.add(items[i])
}
}
return result.toList()
}
/*
main demonstrates the function with a simple example.
Keeping main small and focused makes the program easy to extend.
*/
fun main() {
val data: List<Int> = (1..20).toList() // Example list: numbers 1–20
val n: Int = 3 // Remove every 3rd element
val cleaned: List<Int> = removeEveryNth(data, n)
println("Original: ${data.joinToString(" ")}")
println("After removing every $n-th element: ${cleaned.joinToString(" ")}")
}
/*
run:
Original: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
After removing every 3-th element: 1 2 4 5 7 8 10 11 13 14 16 17 19 20
*/
