Simple Fun #176: Reverse Letter

//Given a string str, reverse it omitting all non-alphabetic characters.
//Example

//For str = "krishan", the output should be "nahsirk".

//For str = "ultr53o?n", the output should be "nortlu".
//Input/Output

//    [input] string str

//    A string consists of lowercase latin letters, digits and symbols.

//    [output] a string
//////////////////////////////////////////
//Solution:

fun reverseLetter(str: String): String {
  return str.reversed().replace("""[^a-z]""".toRegex(), "")
}

// best solutions:
fun reverseLetter(str: String): String {
    return str.filter(Char::isLetter).reversed()
}

fun reverseLetter(str: String): String {
  return str.replace(Regex("[^a-zA-Z]"), "").reversed()
}