I have some list of instances of some custom class:
data class Flight(val duration: Int)
For example:
val flights = listOf(Flight(10), Flight(5), Flight(5), Flight(15), Flight(20))
How to most effectively find first index of the minimum element in this list? In that case the first index of min element is 1, because flights[1].duration = 5.
Something like this would be "most efficient", I guess:
var min: Pair<Int, Flight>? = null
for (f in flights.withIndex()) {
if (min == null || min.second.duration > f.value.duration) min = f.index to f.value
}
And this one does basically the same and looks much better:
flights.withIndex().minBy { (_, f) -> f.duration }?.index
With minBy() to get the list item with the minimum duration
and then indexOf() to get its index:
val index = flights.indexOf(flights.minBy { it.duration })
For just 1 scan of the list, you can do a classic loop:
var index = if (flights.isEmpty()) -1 else 0
flights.forEachIndexed { i, flight ->
if (flight.duration < flights[index].duration) index = i
}
Try
val index = flights.minBy { it.duration }?.let { flights.indexOf(it) }