From 83caee03926dfbad0f6b3dfc734655212c58111e Mon Sep 17 00:00:00 2001
From: Jinyeong Seol <wlsdud5654@gmail.com>
Date: Mon, 27 Oct 2025 23:47:48 +0900
Subject: [PATCH] =?UTF-8?q?[20251027]=20BOJ=20/=20G5=20/=20=EC=88=AB?=
 =?UTF-8?q?=EC=9E=90=EA=B3=A0=EB=A5=B4=EA=B8=B0=20/=20=EC=84=A4=EC=A7=84?=
 =?UTF-8?q?=EC=98=81?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 ...20\352\263\240\353\245\264\352\270\260.md" | 74 +++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 "Seol-JY/202510/27 BOJ \354\210\253\354\236\220\352\263\240\353\245\264\352\270\260.md"

diff --git "a/Seol-JY/202510/27 BOJ \354\210\253\354\236\220\352\263\240\353\245\264\352\270\260.md" "b/Seol-JY/202510/27 BOJ \354\210\253\354\236\220\352\263\240\353\245\264\352\270\260.md"
new file mode 100644
index 00000000..472ca684
--- /dev/null
+++ "b/Seol-JY/202510/27 BOJ \354\210\253\354\236\220\352\263\240\353\245\264\352\270\260.md"	
@@ -0,0 +1,74 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    static int N;
+    static int[] next;
+    static boolean[] finished;
+    static boolean[] inCycle;
+    
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+        
+        N = Integer.parseInt(br.readLine());
+        next = new int[N + 1];
+        finished = new boolean[N + 1];
+        inCycle = new boolean[N + 1];
+        
+        for (int i = 1; i <= N; i++) {
+            next[i] = Integer.parseInt(br.readLine());
+        }
+        
+        for (int i = 1; i <= N; i++) {
+            if (!finished[i]) {
+                boolean[] visited = new boolean[N + 1];
+                int current = i;
+                List<Integer> path = new ArrayList<>();
+                
+                while (!visited[current] && !finished[current]) {
+                    visited[current] = true;
+                    path.add(current);
+                    current = next[current];
+                }
+                
+                if (!finished[current]) {
+                    int cycleStart = current;
+                    boolean inCycleNow = false;
+                    
+                    for (int node : path) {
+                        if (node == cycleStart) {
+                            inCycleNow = true;
+                        }
+                        if (inCycleNow) {
+                            inCycle[node] = true;
+                        }
+                        finished[node] = true;
+                    }
+                } else {
+                    for (int node : path) {
+                        finished[node] = true;
+                    }
+                }
+            }
+        }
+        
+        List<Integer> result = new ArrayList<>();
+        for (int i = 1; i <= N; i++) {
+            if (inCycle[i]) {
+                result.add(i);
+            }
+        }
+        
+        bw.write(result.size() + "\n");
+        for (int num : result) {
+            bw.write(num + "\n");
+        }
+        
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+}
+```