231002 카카오프렌즈 컬러링북

private final int[] dx = { -1, 0, 1, 0 };
private final int[] dy = { 0, 1, 0, -1 };
private boolean[][] visited;

public int[] solution(int m, int n, int[][] picture) {
	int numberOfArea = 0;
	int maxSizeOfOneArea = 0;
	visited = new boolean[m][n];

	for (int i = 0; i < m; i++) {
		for (int j = 0; j < n; j++) {
			if (picture[i][j] != 0 && !visited[i][j]) {
				int size = bfs(m, n, i, j, picture);
				maxSizeOfOneArea = Math.max(maxSizeOfOneArea, size);
				numberOfArea++;
			}
		}
	}

	return new int[] { numberOfArea, maxSizeOfOneArea };
}

private int bfs(int m, int n, int startX, int startY, int[][] picture) {
	int size = 1;
	int targetColor = picture[startX][startY];
	Queue<Point> queue = new LinkedList<>();
	visited[startX][startY] = true;
	queue.offer(new Point(startX, startY));

	while (!queue.isEmpty()) {
		Point currentPoint = queue.poll();

		for (int i = 0; i < 4; i++) {
			int nextX = currentPoint.getX() + dx[i];
			int nextY = currentPoint.getY() + dy[i];

			if (isValidPosition(m, n, nextX, nextY) && picture[nextX][nextY] == targetColor
					&& !visited[nextX][nextY]) {
				queue.offer(new Point(nextX, nextY));
				visited[nextX][nextY] = true;
				size++;
			}
		}
	}

	return size;
}

private boolean isValidPosition(int m, int n, int x, int y) {
	return x >= 0 && x < m && y >= 0 && y < n;
}

private static class Point {
	private int x;
	private int y;

	public Point(int x, int y) {
		this.x = x;
		this.y = y;
	}

	public int getX() {
		return x;
	}

	public int getY() {
		return y;
	}
}

출처:https://school.programmers.co.kr/learn/courses/30/lessons/1829