241023 축구 전술

public static void main(String[] args) throws NumberFormatException, IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	StringBuilder sb = new StringBuilder();

	int testCases = Integer.parseInt(br.readLine());

	for (int testCase = 0; testCase < testCases; testCase++) {
		StringTokenizer st = new StringTokenizer(br.readLine());
		int n = Integer.parseInt(st.nextToken());
		int m = Integer.parseInt(st.nextToken());

		boolean[] visited = new boolean[n];
		List<List<Integer>> graph = new ArrayList<>();
		List<List<Integer>> transposition = new ArrayList<>();

		for (int i = 0; i < n; i++) {
			graph.add(new ArrayList<>());
			transposition.add(new ArrayList<>());
		}

		for (int i = 0; i < m; i++) {
			st = new StringTokenizer(br.readLine());
			int from = Integer.parseInt(st.nextToken());
			int to = Integer.parseInt(st.nextToken());
			graph.get(from).add(to);
			transposition.get(to).add(from);
		}

		if (testCase < testCases - 1) {
			br.readLine();
		}

		Stack<Integer> stack = new Stack<>();

		for (int i = 0; i < n; i++) {
			if (!visited[i]) {
				postOrder(i, graph, visited, stack);
			}
		}

		int root = stack.pop();
		visited = new boolean[n];
		postOrder(root, graph, visited, new Stack<>());

		boolean allVisited = true;
		for (int i = 0; i < n; i++) {
			if (!visited[i]) {
				sb.append("Confused\n\n");
				allVisited = false;
				break;
			}
		}

		if (allVisited) {
			List<Integer> list = new ArrayList<>();
			dfs(root, transposition, visited, list);
			list.sort(null);

			for (int value : list) {
				sb.append(value).append("\n");
			}
			sb.append("\n");
		}
	}

	System.out.println(sb);
}

static void postOrder(int v, List<List<Integer>> graph, boolean[] visited, Stack<Integer> stack) {
	visited[v] = true;
	for (int next : graph.get(v)) {
		if (!visited[next]) {
			postOrder(next, graph, visited, stack);
		}
	}
	stack.push(v);
}

static void dfs(int v, List<List<Integer>> transposition, boolean[] visited, List<Integer> list) {
	Stack<Integer> s = new Stack<>();
	s.push(v);
	visited[v] = false;

	list.add(v);

	while (!s.isEmpty()) {
		int cur = s.pop();
		for (int next : transposition.get(cur)) {
			if (visited[next]) {
				visited[next] = false;
				s.push(next);
				list.add(next);
			}
		}
	}
}

출처:https://www.acmicpc.net/problem/3977