Updating Sets

Part of the Logic & Flow section of Coddy's Kotlin journey. Lesson 12 of 63.

Mutable sets support add and remove. Adding an existing value or removing an absent value leaves membership unchanged. The Boolean result tells you whether the set changed.

Inside main:

val tags = mutableSetOf("a", "b")
println(tags.add("a"))

The a tag was already present, so add reports no change.

Set add and remove return whether membership actually changed.

Challenge

Medium

Complete addUnique with parameters items: List<Int>, value: Int. Copy the items to a mutable set, add value, and return whether it was newly added.

Unless stricter bounds are stated above, collections contain at most 100 elements at each level, and integer arguments and integer collection values are between -1000 and 1000. Text supplied for parsing can include invalid or out-of-range representations as described.

Return a value of type Boolean. Keep the supplied input/output code. It reads scalar arguments one per line; a list starts with its count followed by its elements, and a map starts with its entry count followed by each key and value. Nested lists repeat the count-and-elements format for each row. The supplied main prints the return value followed by one newline. Lists use Kotlin's standard bracketed format; print no additional labels.

Try it yourself

fun addUnique(items: List<Int>, value: Int): Boolean {
    // Write your solution here.
    return false
}
fun main() {
    val itemsCount = readln().toInt()
    val items = mutableListOf<Int>()
    for (i0 in 0 until itemsCount) {
        val itemsItem = readln().toInt()
        items.add(itemsItem)
    }
    val value = readln().toInt()
    println(addUnique(items, value))
}