Super Reduced String - https://www.hackerrank.com/challenges/reduced-string/problem

SuperReducedString.swift

import Foundation

var text = "baabc"

func removeDuplicatedCharacters(in text: String) -> String {
    var other = text
    var uniqueChars = [String]()
    
    for char in other.characters {
        let current = char.description
        if !uniqueChars.contains(current) {
            uniqueChars.append(current)
        }
    }
    
    for char in uniqueChars {
        let dup = "\(char)\(char)"
        
        if other.contains(dup) {
            other = other.replacingOccurrences(of: dup, with: "")
            other = removeDuplicatedCharacters(in: other)
        }
    }
    
    if other == "" {
        other = "Empty String"
    }
    
    return other
}

print(removeDuplicatedCharacters(in: text))