diff --git a/BOJ-ios/README.md b/BOJ-ios/README.md
index 713d2dc..2f8877f 100644
--- a/BOJ-ios/README.md
+++ b/BOJ-ios/README.md
@@ -6,4 +6,5 @@
 | 2차시 | 2024.03.22 | 라빈카프 | [반복 부분문자열](https://www.acmicpc.net/problem/1605) [가장 긴 문자열](https://www.acmicpc.net/problem/3033) |  [#8](https://github.com/AlgoLeadMe/AlgoLeadMe-9/pulls/8)  |
 | 3차시 | 2024.03.26 | 펜윅트리 |                             [구간 합 구하기](https://www.acmicpc.net/problem/2042)                             | [#13](https://github.com/AlgoLeadMe/AlgoLeadMe-9/pulls/13) |
 | 4차시 | 2024.03.30 | 볼록껍질 |                               [볼록 껍질](https://www.acmicpc.net/problem/1708)                                | [#14](https://github.com/AlgoLeadMe/AlgoLeadMe-9/pulls/14) |
-| 5차시 | 2025.04.29 |  스위핑  |               [여러 직사각형의 전체 면적 구하기](https://www.acmicpc.net/problem/2672)                          | [#19](https://github.com/AlgoLeadMe/AlgoLeadMe-9/pulls/19) |
\ No newline at end of file
+| 5차시 | 2024.04.29 |  스위핑  |                    [여러 직사각형의 전체 면적 구하기](https://www.acmicpc.net/problem/2672)                    | [#19](https://github.com/AlgoLeadMe/AlgoLeadMe-9/pulls/19) |
+| 6차시 | 2024.05.13 | 위상정렬 |                               [줄 세우기](https://www.acmicpc.net/problem/2252)                                | [#20](https://github.com/AlgoLeadMe/AlgoLeadMe-9/pulls/20) |
\ No newline at end of file
diff --git "a/BOJ-ios/\354\234\204\354\203\201\354\240\225\353\240\254/P2252\353\262\210_\354\244\204_\354\204\270\354\232\260\352\270\260/Main.java" "b/BOJ-ios/\354\234\204\354\203\201\354\240\225\353\240\254/P2252\353\262\210_\354\244\204_\354\204\270\354\232\260\352\270\260/Main.java"
new file mode 100644
index 0000000..6493f8c
--- /dev/null
+++ "b/BOJ-ios/\354\234\204\354\203\201\354\240\225\353\240\254/P2252\353\262\210_\354\244\204_\354\204\270\354\232\260\352\270\260/Main.java"
@@ -0,0 +1,53 @@
+package BAEKJOON.Gold.Gold_III.P2252번_줄_세우기;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.LinkedList;
+import java.util.Queue;
+import java.util.StringTokenizer;
+
+public class Main {
+    protected static int[] inDegree;
+    protected static LinkedList<Integer>[] graph;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        int N = Integer.parseInt(st.nextToken());
+        int M = Integer.parseInt(st.nextToken());
+        inDegree = new int[N + 1];
+        graph = new LinkedList[N + 1];
+        for (int i = 0; i < N + 1; i++) {
+            graph[i] = new LinkedList<>();
+        }
+        for (int j = 0; j < M; j++) {
+            st = new StringTokenizer(br.readLine());
+            int A = Integer.parseInt(st.nextToken());
+            int B = Integer.parseInt(st.nextToken());
+            graph[A].add(B);
+            inDegree[B]++;
+        }
+        System.out.println(topologySort(N));
+    }
+
+    public static String topologySort(int N) {
+        StringBuilder sb = new StringBuilder();
+        Queue<Integer> queue = new LinkedList<>();
+        for (int i = 1; i < N + 1; i++) {
+            if (inDegree[i] == 0) {
+                queue.add(i);
+            }
+        }
+        while (!queue.isEmpty()) {
+            int now = queue.poll();
+            sb.append(now).append(' ');
+            for (int next : graph[now]) {
+                if (--inDegree[next] == 0) {
+                    queue.add(next);
+                }
+            }
+        }
+        return sb.toString();
+    }
+}