uploaded at 2022. 12. 29. 오전 7:13:28

programmers/오픈채팅방/solution.java

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+// [문제 링크]: https://school.programmers.co.kr/learn/courses/30/lessons/42888
+
+import java.util.HashMap;
+import java.lang.StringBuilder;
+import java.util.ArrayList;
+class Solution {
+    public String[] solution(String[] record) {
+        HashMap<String,String> hm = new HashMap<>();
+        ArrayList<String> al = new ArrayList<>(), al2 = new ArrayList<>();
+        StringBuilder sb = new StringBuilder();
+        for(String r : record){
+            String[] temp = r.split(" ");
+            String job = temp[0], uid = temp[1], name = "", msg="";
+            if(temp.length==3) {
+                name = temp[2];
+                hm.put(uid,name);
+            }
+            switch(job){
+                case "Enter":
+                    msg = "님이 들어왔습니다.";
+                    break;
+                case "Leave":
+                    msg = "님이 나갔습니다.";
+                    break;
+            }
+            if(!msg.equals("")) {
+                al.add(uid);
+                al2.add(msg);
+            }
+        }
+        for(int a = 0; a < al.size(); a++){
+            sb.append(hm.get(al.get(a)));
+            sb.append(al2.get(a));
+            al.set(a,sb.toString());
+            sb.setLength(0);
+        }
+        return al.toArray(String[]::new);
+    }
+}