/**
* Returns the N-th digit of a number counting from the right.
*
* Examples:
* getNthDigitFromRight(12345, 1) == 5
* getNthDigitFromRight(12345, 2) == 4
* getNthDigitFromRight(12345, 3) == 3
*
* @param inputNumber The number to inspect.
* @param digitPosition The digit position (1-based, from the right).
* @return The digit at the specified position.
* @throws IllegalArgumentException If digitPosition is less than 1.
*/
fun getNthDigitFromRight(inputNumber: Long, digitPosition: Int): Int {
require(digitPosition > 0) {
"Digit position must be greater than 0."
}
// Handle negative numbers.
val absoluteNumber = kotlin.math.abs(inputNumber)
// Calculate 10^(digitPosition - 1) using integer arithmetic.
var divisor = 1L
for (positionIndex in 1 until digitPosition) {
divisor *= 10
}
// Shift the desired digit to the ones place.
val shiftedNumber = absoluteNumber / divisor
// Extract the digit.
return (shiftedNumber % 10).toInt()
}
fun main() {
val inputNumber = 12745L
val firstDigitFromRight =
getNthDigitFromRight(inputNumber, 1)
val thirdDigitFromRight =
getNthDigitFromRight(inputNumber, 3)
val fifthDigitFromRight =
getNthDigitFromRight(inputNumber, 5)
println("Number: $inputNumber")
println("1st digit from right: $firstDigitFromRight")
println("3rd digit from right: $thirdDigitFromRight")
println("5th digit from right: $fifthDigitFromRight")
}
/*
run:
Number: 12745
1st digit from right: 5
3rd digit from right: 7
5th digit from right: 1
*/
