[프로그래밍] 프로그래머스 예제문제 풀어보기 <오픈채팅방> (성공)

import java.util.List;
import java.util.HashMap;
import java.util.ArrayList;
 
class Solution {
    public String[] solution(String[] record) {
            List<String> answerArr = new ArrayList<>();
            HashMap<String,String> idMap = new HashMap<>();
        for(String rec:record) {
            if(rec.startsWith("Enter")) {
                idMap.put(rec.split(" ")[1],rec.split(" ")[2]);
                
            }else if(rec.startsWith("Change")) {
                idMap.put(rec.split(" ")[1],rec.split(" ")[2]);                
            }
        }
        
        for(String rec: record) {
            if(rec.startsWith("Enter")) {
                answerArr.add(idMap.get(rec.split(" ")[1])+"님이 들어왔습니다.");
                
            }else if(rec.startsWith("Leave")) {
                answerArr.add(idMap.get(rec.split(" ")[1])+"님이 나갔습니다.");
                
            }        
        }
            
        String[] answer = new String[answerArr.size()];
        for(int i =0 ; i<answerArr.size();i++) {
            answer[i] = answerArr.get(i);
            }
        
        
        return answer;
    }
}