241212 Dangerous Dive

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

	int[] input = readInput(br);
	int n = input[0];
	int r = input[1];

	if (n == r) {
		sb.append("*");
	} else {
		boolean[] returned = markReturnedPeople(br, r, n);
		listMissingPeople(sb, returned);
	}
	System.out.print(sb);
}

private static int[] readInput(BufferedReader br) throws IOException {
	StringTokenizer st = new StringTokenizer(br.readLine());
	int n = Integer.parseInt(st.nextToken());
	int r = Integer.parseInt(st.nextToken());
	return new int[] { n, r };
}

private static boolean[] markReturnedPeople(BufferedReader br, int r, int n) throws IOException {
	boolean[] returned = new boolean[n + 1];
	StringTokenizer st = new StringTokenizer(br.readLine());
	for (int i = 0; i < r; i++) {
		int person = Integer.parseInt(st.nextToken());
		returned[person] = true;
	}
	return returned;
}

private static void listMissingPeople(StringBuilder sb, boolean[] returned) {
	for (int i = 1; i < returned.length; i++) {
		if (!returned[i]) {
			sb.append(i).append(" ");
		}
	}
	if (sb.length() > 0) {
		sb.setLength(sb.length() - 1);
	}
}

출처:https://www.acmicpc.net/problem/13627