250101 로봇 청소기

private static final char WALL = '1';
private static final char EMPTY = '0';
private static final char CLEANED = '2';

private static int cleanRoom(int position, int direction, int[] delta, char[] map) {
	int count = 1;
	map[position] = CLEANED;

	while (true) {
		boolean cleaned = false;

		for (int i = 0; i < 4; i++) {
			direction = turnLeft(direction);
			int nextPos = position + delta[direction];

			if (map[nextPos] == EMPTY) {
				map[nextPos] = CLEANED;
				position = nextPos;
				count++;
				cleaned = true;
				break;
			}
		}

		if (!cleaned) {
			int backPos = position + delta[(direction + 2) & 3];
			if (map[backPos] == WALL) {
				break;
			}
			position = backPos;
		}
	}
	return count;
}

private static int turnLeft(int direction) {
	return (direction + 3) & 3;
}

public static void main(String[] args) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	StringTokenizer st = new StringTokenizer(br.readLine(), " ");

	int rows = Integer.parseInt(st.nextToken());
	int cols = Integer.parseInt(st.nextToken());
	int mapWidth = cols * 2;

	st = new StringTokenizer(br.readLine(), " ");
	int startRow = Integer.parseInt(st.nextToken());
	int startCol = Integer.parseInt(st.nextToken());
	int direction = Integer.parseInt(st.nextToken());

	char[] map = new char[rows * mapWidth];
	br.read(map, 0, rows * mapWidth - 1);

	int cleanedArea = cleanRoom(startRow * mapWidth + (startCol * 2), direction,
			new int[] { -mapWidth, 2, mapWidth, -2 }, map);
	System.out.print(cleanedArea);
}

출처:https://www.acmicpc.net/problem/14503