// Finds the last repeated character in a string.
// Scans the string from right to left using a MutableSet to track seen characters.
// Returns the character, or ' ' if no character is repeated.
fun findLastRepeatedCharacter(s: String): Char {
val seen = mutableSetOf<Char>()
// Iterate through the string's characters from right to left
for (c in s.reversed()) {
// MutableSet.add() returns false if the element was already present in the set.
// This checks existence and adds the element in a single efficient operation.
if (!seen.add(c)) {
return c
}
}
// Return a space character if no duplicates are found (matching C++ style)
return ' '
}
fun main() {
// Test cases adapted from your C++ examples
val testCases = listOf(
"abca",
"abcbd",
"abcde",
"abcdxypcbop",
"abcdxypcbadom"
)
for (tc in testCases) {
val result = findLastRepeatedCharacter(tc)
println("findLastRepeatedCharacter(\"$tc\") -> $result")
}
}
/*
run:
findLastRepeatedCharacter("abca") -> a
findLastRepeatedCharacter("abcbd") -> b
findLastRepeatedCharacter("abcde") ->
findLastRepeatedCharacter("abcdxypcbop") -> p
findLastRepeatedCharacter("abcdxypcbadom") -> d
*/
