240127 빛의 경로 사이클

public int[] solution(String[] grid) {
	int rows = grid.length;
	int cols = grid[0].length();

	boolean[][][] visited = new boolean[rows][cols][4];
	List<Integer> distances = new ArrayList<>();

	int[] directionsRow = { -1, 0, 1, 0 };
	int[] directionsCol = { 0, -1, 0, 1 };

	for (int row = 0; row < rows; row++) {
		for (int col = 0; col < cols; col++) {
			for (int dir = 0; dir < 4; dir++) {
				if (!visited[row][col][dir]) {
					int distance = explore(grid, row, col, dir, visited, directionsRow, directionsCol);
					distances.add(distance);
				}
			}
		}
	}

	return distances.stream().sorted().mapToInt(Integer::intValue).toArray();
}

private int explore(String[] grid, int row, int col, int dir, boolean[][][] visited, int[] directionsRow,
		int[] directionsCol) {
	int distance = 0;
	while (!visited[row][col][dir]) {
		distance++;
		visited[row][col][dir] = true;

		char cell = grid[row].charAt(col);
		dir = updateDirection(cell, dir);

		row = (row + directionsRow[dir] + grid.length) % grid.length;
		col = (col + directionsCol[dir] + grid[0].length()) % grid[0].length();
	}
	return distance;
}

private int updateDirection(char cell, int dir) {
	if (cell == 'L') {
		dir = (dir + 3) % 4;
	} else if (cell == 'R') {
		dir = (dir + 1) % 4;
	}
	return dir;
}

출처:https://school.programmers.co.kr/learn/courses/30/lessons/86052