package workingon; import java.io.*; import java.util.*; public class BOJ1325_효율적인해킹 { static ArrayList res = new ArrayList(); static ArrayList[] arr; static boolean[] visited; static Queue queue = new LinkedList<>(); 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()); arr = new ArrayList[N+1]; for (int i = 1; i <= N; i++) { arr[i] = new ArrayList<>(); } for (int i = 0; i < M; i++) { st = new StringTokenizer(br.readLine()); int A = Integer.parseInt(st.nextToken()); int B = Integer.parseInt(st.nextToken()); arr[B].add(A); } // System.out.println(Arrays.toString(arr)); int max = 0; PriorityQueue pq = new PriorityQueue<>(); for(int i = 1 ; i <= N ; i++) { // System.out.println("i = " + i + "일 때"); visited = new boolean[N+1]; int res = bfs(i, 0); if(res > max) { pq.poll(); pq.offer(i); max = res; // System.out.println("PQ : " + pq); } else if(max == res) { pq.offer(i); // System.out.println("PQ : " + pq); } } while(!pq.isEmpty()) { System.out.print(pq.poll()+" "); } } public static int bfs(int start, int depth){ queue.offer(start); visited[start] = true; while(!queue.isEmpty()) { ++depth; // System.out.println("현재 큐 : " + queue); // System.out.println("현재 depth : " + depth); int cur = queue.poll(); for(int i = 0 ; i < arr[cur].size() ; i++) { if(!visited[arr[cur].get(i)]) { queue.offer(arr[cur].get(i)); visited[arr[cur].get(i)] = true; } } } // System.out.println("depth : " + depth); return depth; } }

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