Sets, pairs and destructuring

A club membership list should avoid duplicate entries, while a small result can carry a total and count together. Set represents unique elements. Pair and Triple package a fixed number of values, and destructuring gives their components local names.

Set intersection finds shared members, union combines membership and subtraction removes members. Do not rely on every set implementation having one display order. Destructuring follows component functions; a Pair’s first and second positions are not domain-specific names by themselves.

Save the complete source as Main.kt and use the Kotlin/JVM environment. No separate input file is needed.

Kotlin/JVM · complete program

fun main() {
  val art = setOf("Diya", "Saira", "Diya")
  val music = setOf("Saira", "Noor")
  println((art intersect music).sorted())
  val (total, count) = 160 to 2
  println(total / count)
}

Expected output

[Saira]
80

Follow the execution

Duplicate Diya contributes only one set member. The sorted intersection contains Saira. The infix to function forms a Pair, whose two components become total and count. Their integer division is 80.

Try this in the Kotlin compiler by pasting the complete program.

Your task: Which collection should preserve repeated attendance entries in their original order?

Kotlin/JVM · complete program

fun main() {
  val art = setOf("Diya", "Saira", "Diya")
  val music = setOf("Saira", "Noor")
  println((art intersect music).sorted())
  val (total, count) = 160 to 2
  println(total / count)
}

Worked answer

A list should. A set removes duplicates and does not offer a universal original-order guarantee.

For a meaningful long-lived report model, a named data class can be clearer than a Pair. Set uniqueness follows equality and hashing rules, not proof that equal display names belong to one person.

A list should. A set removes duplicates and does not offer a universal original-order guarantee. For a meaningful long-lived report model, a named data class can be clearer than a Pair.

Further reading: official Kotlin documentation for this topic.