How do I use "for" for this case - kotlin

Question

I need this function to look in a file for a certain day, then say for each flight how many people are there, in the same day.
So far I managed to get it to say how many people there are per day, but im struggling to get it to say how many people are on each flight per day.
fun interval(reserves: ArrayList<Reserves>, dayInferior: Int, daySuperior: Int) {
var count = dayInferior
var person: Int
for (reserve in reserves) {
person = 0
for (reserve in reserves) {
if (reserve.day == count && reserve.day <= daySuperior) {
person++
}
}
if (count <= daySuperior) {
println("${reserve.numFlight} Day $count has $person")
}
count++
}
}
class Reserves {
var numCc: Int?
var name: String
var numFlight: String
var day: Int
constructor(numCc: Int?, name: String, numFlight: String, day: Int) {
this.numCc = numCc
this.name = name
this.numFlight = numFlight
this.day = day
}
}
fun readFileReserves(fileNameInput: String): ArrayList<Reserves> {
val reserves: ArrayList<Reserves> = ArrayList()
val lines = File(fileNameInput).readLines()
for (line in lines) {
val parts = line.split(':')
val numCc = parts[0].toIntOrNull()
val name = parts[1]
val numFlight = parts[2]
val day = parts[3].toIntOrNull()
if (day == null || numCc == null) {
println("Invalid day")
} else {
val r = Reserves(numCc, name, numFlight, day)
reserves.add(r)
}
}
return reserves
}

Answer 1

I assume #Jocas means interval to get the count of Reserves between dayInferior and daySuperior.
fun interval(reserves: List<Reserves>, dayInferior: Int, daySuperior: Int) {
val map = mapReserves(reserves)
for(day in dayInferior..daySuperior) {
map.forEach {
val reservesName = it.key.first
val reservesDay = it.key.second
val reservesCount = it.value.count()
if (reservesDay == day)
print("$reservesName has $reservesCount on day passengers $day")
}
}
}
fun mapReserves(reserves: List<Reserves>): Map<Pair<String, Int>, List<Reserves>> {
val map = mutableMapOf<Pair<String, Int>, MutableList<Reserves>>()
reserves.forEach {
val key = it.numFlight to it.day
val list = map[key] ?: mutableListOf()
list.add(it)
map[key] = list
}
return map
}
// This is how you write in Kotlin. Your style is Java.
class Reserves(var numCc: Int, var name: String, var numFlight: String, var day: Int)
// Use abstraction List and MutableList instead of ArrayList
fun readFileReserves(fileNameInput: String): List<Reserves> {
val reserves = mutableListOf<Reserves>()
val lines = File(fileNameInput).readLines()
for (line in lines) {
val parts = line.split(":")
val numCc = parts[0].toIntOrNull()
val name = parts[1]
val numFlight = parts[2]
val day = parts[3].toIntOrNull()
if (day == null || numCc == null) {
println("Invalid day")
} else {
val r = Reserves(numCc, name, numFlight, day)
reserves.add(r)
}
}
return reserves
}