The challenge
Given a string str, reverse it omitting all non-alphabetic characters.
Examples:
For str = "krishan", the output should be "nahsirk".
For str = "ultr53o?n", the output should be "nortlu".
Input/Output:
[input]stringstr
A string consists of lowercase Latin letters, digits, and symbols.
[output]a string
The solution in Kotlin
Option 1:
fun reverseLetter(str: String): String {
return str.filter(Char::isLetter).reversed()
}
Option 2:
fun reverseLetter(str: String) = str.reversed().filter{ it.isLetter() }
Option 3:
fun reverseLetter(str: String): String = str.replace(Regex("[^a-zA-Z]"), "").reversed()
Test cases to validate our solution
import kotlin.test.assertEquals
import org.junit.Test
class TestReverseLetter {
@Test
fun `Basic Tests` () {
val str = "krishan"
assertEquals("nahsirk", reverseLetter("krishan"))
assertEquals("nortlu", reverseLetter("ultr53o?n"))
assertEquals("cba", reverseLetter("ab23c"))
assertEquals("nahsirk", reverseLetter("krish21an"))
}
}
