Reading multiple ints from the same line in Kotlin? - kotlin

Question

I am doing the 30 Days of Code in Kotlin on Hackerrank and I am stuck at Day 7.
How do you read multiple integers on a single line?
How is it added to an array and displayed in reverse?
I have solved it in Java but lack the syntax needed in Kotlin
Input:
4
1 4 3 2
My Code:
fun main(args: Array<String>) {
val n = readLine()!!.toInt()
var arr = Array(n)
for(i in 0 until n)
{
arr[i] = readLine()!!.toInt() //Not Working? nor does readLine()!!.split(' ').toInt()
}
for(item in arr.size - 1 downTo 0)
{
print("${item} ")
}
}

Answer 1

EDIT: question was updated from the original
The problem is the readLine() will read the entire line from stdin, so each time you call readLine() in the for loop it will result in a separate line being read each time.
One approach to this is to read the line, and then to split and map each value to an Int.
readLine()?.let {
val numOfValues = it.toInt()
println(numOfValues)
readLine()?.let { line ->
line.split(" ").map {
it.toInt()
}.reversed().forEach {
println(it)
}
}
}

Answer 2

If you want to store them in a list then you can follow this method
var items = readLine()!!.trim().split("\\s+".toRegex()).map (String::toInt)
println(items)
You can also store them in different variables like this way
var (a,b) = readLine()!!.trim().split("\\s+".toRegex()).map (String::toInt)
println(a+b)

Answer 3

You can also use the following code to item items splited and stored in array for a beginner approach
fun main(ags :Array<String>)
{
var item = readLine()!!.trim()
println(item[0])
}

Answer 4

Actually, you can refer to the official Kotlin tutorial: https://kotlinlang.org/docs/tutorials/competitive-programming.html
as mentioned in tutorial:
To make reading the input in competitive programming tasks like this more concise, you can have the following list of helper input-reading functions:
private fun readLn() = readLine()!! // string line
private fun readInt() = readLn().toInt() // single int
private fun readStrings() = readLn().split(" ") // list of strings
private fun readInts() = readStrings().map { it.toInt() } // list of ints
for your case, you can try use as below:
fun main() {
val n = readInt()
val x = readInts()
for (j in x.reversed()) {
print(j); print(" ")
}
println()
}
private fun readLn() = readLine()!! // string line
private fun readInt() = readLn().toInt() // single int
private fun readStrings() = readLn().split(" ") // list of strings
private fun readInts() = readStrings().map { it.toInt() } // list of ints