// A function that finds the two largest elements in an iterable collection.
// Returns a Pair of (largest, secondLargest), or null if the collection has fewer than 2 elements.
fun findTwoLargest(numbers: Iterable<Int>): Pair<Int, Int>? {
val iterator = numbers.iterator()
// Guard clause: ensure there is at least a first element
if (!iterator.hasNext()) return null
var largest = iterator.next()
// Guard clause: ensure there is at least a second element
if (!iterator.hasNext()) return null
var secondLargest = iterator.next()
// Ensure initial assignment properly sorts the first two elements
if (secondLargest > largest) {
val temp = largest
largest = secondLargest
secondLargest = temp
}
// Iterate through the remainder of the collection in a single O(N) pass
for (num in iterator) {
if (num > largest) {
// New absolute maximum found; old max shifts down to second largest
secondLargest = largest
largest = num
} else if (num > secondLargest) {
// Greater than second largest, but not the absolute maximum
secondLargest = num
}
}
return Pair(largest, secondLargest)
}
fun main() {
// Define the dataset using a Kotlin list
val data = listOf(3, 4, 9, 6, 7, 1, 2, 5)
// Call our function and handle the nullable Pair result idiomatically
val result = findTwoLargest(data)
if (result != null) {
println("Dataset: $data")
println("The largest element is: ${result.first}")
println("The second largest element is: ${result.second}")
} else {
println("Error: The collection must contain at least two elements.")
}
}
/*
run:
Dataset: [3, 4, 9, 6, 7, 1, 2, 5]
The largest element is: 9
The second largest element is: 7
*/
