프로그래머스 중복된 문자 제거 (JAVA)

https://school.programmers.co.kr/learn/courses/30/lessons/120888

프로그래머스

 

 

 

import java.util.*;
class Solution {
    public String solution(String my_string) {
        String answer = "";
        StringBuilder sb = new StringBuilder();
        Set<Character> check = new HashSet<>();
        for(int i = 0 ; i < my_string.length() ; i++){
            char ch = my_string.charAt(i);
            if(!check.contains(ch)){
                check.add(ch);
                sb.append(ch);
            }
        }
        answer = sb.toString();
        return answer;
    }
}