diff --git "a/Seol-JY/202502/20 SWEA D4 \353\217\231\354\225\204\353\246\254\354\213\244 \352\264\200\353\246\254\355\225\230\352\270\260.md" "b/Seol-JY/202502/20 SWEA D4 \353\217\231\354\225\204\353\246\254\354\213\244 \352\264\200\353\246\254\355\225\230\352\270\260.md"
new file mode 100644
index 00000000..49d55414
--- /dev/null
+++ "b/Seol-JY/202502/20 SWEA D4 \353\217\231\354\225\204\353\246\254\354\213\244 \352\264\200\353\246\254\355\225\230\352\270\260.md"	
@@ -0,0 +1,46 @@
+```java
+import java.io.*;
+
+public class Solution {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        int testCases = Integer.parseInt(br.readLine());
+        for (int tc = 1; tc <= testCases; tc++) {
+            String sequence = br.readLine();
+            System.out.println("#" + tc + " " + solve(sequence, sequence.length()));
+        }
+    }
+
+    private static int solve(String sequence, int length) {
+        int[][] dp = new int[16][length];
+        final int MOD = 1_000_000_007;
+
+        int firstState = (1 << (sequence.charAt(0) - 'A')) | 1;
+        for (int state = 1; state <= 15; state++) {
+            if ((state & firstState) == firstState) {
+                dp[state][0] = 1;
+            }
+        }
+
+        for (int pos = 1; pos < length; pos++) {
+            int currentPerson = 1 << (sequence.charAt(pos) - 'A');
+            for (int currState = 1; currState <= 15; currState++) {
+                if ((currState & currentPerson) == currentPerson) {
+                    for (int prevState = 1; prevState <= 15; prevState++) {
+                        if (dp[prevState][pos-1] > 0 && ((currState & prevState) > 0)) {
+                            dp[currState][pos] = (dp[currState][pos] + dp[prevState][pos-1]) % MOD;
+                        }
+                    }
+                }
+            }
+        }
+
+        int result = 0;
+        for (int state = 1; state <= 15; state++) {
+            result = (result + dp[state][length-1]) % MOD;
+        }
+        return result;
+    }
+}
+```