diff --git "a/2021 KAKAO BLIND RECRUITMENT/Solution_\353\251\224\353\211\264\353\246\254\353\211\264\354\226\274.java" "b/2021 KAKAO BLIND RECRUITMENT/Solution_\353\251\224\353\211\264\353\246\254\353\211\264\354\226\274.java"
new file mode 100644
index 0000000..ee84239
--- /dev/null
+++ "b/2021 KAKAO BLIND RECRUITMENT/Solution_\353\251\224\353\211\264\353\246\254\353\211\264\354\226\274.java"	
@@ -0,0 +1,105 @@
+import java.io.BufferedReader;
+import java.io.FileInputStream;
+import java.io.InputStreamReader;
+import java.util.*;
+
+public class Solution {
+    static class Word implements Comparable<Word> {
+        String word;
+        int count;
+
+        public Word(String word, int count) {
+            this.word = word;
+            this.count = count;
+        }
+
+        @Override
+        public int compareTo(Word o) {
+            return Integer.compare(o.count, this.count);
+        }
+    }
+
+    static TreeSet<String> result = new TreeSet<>();
+    static PriorityQueue<Word>[] pqs;
+    static char[] chars;
+    static int idx;
+
+    public static void main(String[] args) throws Exception {
+        System.out.println(Arrays.toString(solution(new String[]{"ABCFG", "AC", "CDE", "ACDE", "BCFG", "ACDEH"}, new int[]{2, 3, 4})));
+    }
+
+    public static String[] solution(String[] orders, int[] course) {
+        // 길이 및 오름차순 정렬
+        for (int i = 0; i < orders.length; i++) {
+            char[] charArr = orders[i].toCharArray();
+            Arrays.sort(charArr);
+            orders[i] = new String(charArr);
+        }
+        Arrays.sort(orders, Comparator.comparingInt(String::length));
+
+        pqs = new PriorityQueue[course.length];
+        for (int i = 0; i < pqs.length; i++) {
+            pqs[i] = new PriorityQueue<>();
+        }
+        // course 값의 개수 만큼 조합 시작
+        for (int i = 0; i < course.length; i++) {
+            for (int j = 0; j < orders.length; j++) {
+                chars = new char[course[i]];
+                combination(0, 0, course[i], orders[j], orders);
+            }
+            idx++;
+        }
+
+        for (int i = 0; i < idx; i++) {
+            int max = 0;
+            String str = "";
+            while (!pqs[i].isEmpty()) {
+                Word word = pqs[i].poll();
+                if (word.count == 1 || max > word.count) {
+                    break;
+                }
+
+                if (max < word.count) { // 처음
+                    str = word.word;
+                    max = word.count;
+                    result.add(word.word);
+                } else if (max == word.count && !str.equals(word.word)) { // 개수는 같으나 단어가 다르면
+                    str = word.word;
+                    result.add(word.word);
+                }
+            }
+        }
+
+        String[] answer = new String[result.size()];
+        int i = 0;
+        for (String s : result) {
+            answer[i++] = s;
+        }
+
+        return answer;
+    }
+
+    private static void combination(int cnt, int start, int r, String order, String[] orders) {
+        if (cnt == r) {
+            // 검색 시작
+            int count = 0;
+            for (int i = 0; i < orders.length; i++) {
+                boolean flag = true;
+                for (int j = 0; j < chars.length; j++) {
+                    if (!orders[i].contains(chars[j] + "")) {
+                        flag = false;
+                    }
+                }
+                if (flag) {
+                    count++;
+                }
+            }
+            pqs[idx].offer(new Word(new String(chars), count));
+            return;
+        }
+        for (int i = start; i < order.length(); i++) {
+            chars[cnt] = order.charAt(i);
+            combination(cnt + 1, i + 1, r, order, orders);
+        }
+    }
+}
\ No newline at end of file
diff --git "a/2021 KAKAO BLIND RECRUITMENT/Solution_\354\213\240\352\267\234\354\225\204\354\235\264\353\224\224\354\266\224\354\262\234.java" "b/2021 KAKAO BLIND RECRUITMENT/Solution_\354\213\240\352\267\234\354\225\204\354\235\264\353\224\224\354\266\224\354\262\234.java"
new file mode 100644
index 0000000..2e28323
--- /dev/null
+++ "b/2021 KAKAO BLIND RECRUITMENT/Solution_\354\213\240\352\267\234\354\225\204\354\235\264\353\224\224\354\266\224\354\262\234.java"	
@@ -0,0 +1,57 @@
+import java.io.BufferedReader;
+import java.io.FileInputStream;
+import java.io.InputStreamReader;
+
+public class Solution {
+
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        // 입력 출력
+        System.out.println(solution(br.readLine()));
+    }
+
+    public static String solution(String new_id) {
+        // 1단계
+        new_id = new_id.toLowerCase();
+
+        // 2단계
+        new_id = new_id.replaceAll("[^\\w.\\-_]", "");
+
+        // 3단계
+        new_id = new_id.replaceAll("\\.+", ".");
+
+        // 4단계
+        if (new_id.length() > 0 && new_id.charAt(0) == '.') {
+            StringBuilder sb = new StringBuilder(new_id);
+            sb.deleteCharAt(0);
+            new_id = sb.toString();
+        }
+        if (new_id.length() > 0 && new_id.charAt(new_id.length() - 1) == '.') {
+            StringBuilder sb = new StringBuilder(new_id);
+            sb.deleteCharAt(sb.length() - 1);
+            new_id = sb.toString();
+        }
+
+        // 5단계
+        if (new_id.length() == 0) {
+            new_id = "a";
+        }
+
+        // 6단계
+        if (new_id.length() >= 16) {
+            new_id = new_id.substring(0, 15);
+        }
+        if (new_id.charAt(new_id.length() - 1) == '.') {
+            StringBuilder sb = new StringBuilder(new_id);
+            sb.deleteCharAt(sb.length() - 1);
+            new_id = sb.toString();
+        }
+
+        // 7단계
+        while (new_id.length() <= 2) {
+            new_id += new_id.charAt(new_id.length() - 1);
+        }
+        return new_id;
+    }
+}