240725 미네랄

static int rows;
static int cols;
static char[][] cave;
static boolean[][] onAir;
static int[][] directions = { { 0, -1 }, { -1, 0 }, { 0, 1 }, { 1, 0 } };

public static void main(String[] args) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
	StringTokenizer tokens = new StringTokenizer(br.readLine());
	rows = Integer.parseInt(tokens.nextToken());
	cols = Integer.parseInt(tokens.nextToken());

	cave = new char[rows][cols];
	for (int row = 0; row < rows; row++) {
		String line = br.readLine();
		for (int col = 0; col < cols; col++) {
			cave[row][col] = line.charAt(col);
		}
	}

	int numThrows = Integer.parseInt(br.readLine());
	tokens = new StringTokenizer(br.readLine());
	for (int i = 0; i < numThrows; i++) {
		int level = Integer.parseInt(tokens.nextToken());
		throwBar(rows - level, i);
		dropCluster();
	}

	StringBuilder sb = new StringBuilder();
	for (int row = 0; row < rows; row++) {
		for (int col = 0; col < cols; col++) {
			sb.append(cave[row][col]);
		}
		sb.append("\n");
	}

	bw.write(sb.toString());
	bw.flush();
	bw.close();
}

static void throwBar(int level, int throwCount) {
	if (throwCount % 2 == 0) {
		for (int col = 0; col < cols; col++) {
			if (cave[level][col] == 'x') {
				cave[level][col] = '.';
				break;
			}
		}
	} else {
		for (int col = cols - 1; col >= 0; col--) {
			if (cave[level][col] == 'x') {
				cave[level][col] = '.';
				break;
			}
		}
	}
}

static void dropCluster() {
	onAir = new boolean[rows][cols];
	for (int col = 0; col < cols; col++) {
		if (cave[rows - 1][col] == 'x' && !onAir[rows - 1][col]) {
			onAir[rows - 1][col] = true;
			findConnectedMinerals(rows - 1, col);
		}
	}

	int minDrop = Integer.MAX_VALUE;
	for (int col = cols - 1; col >= 0; col--) {
		minDrop = Math.min(minDrop, findMinDropDistance(col));
	}

	if (minDrop == Integer.MAX_VALUE)
		return;

	for (int row = rows - 2; row >= 0; row--) {
		for (int col = 0; col < cols; col++) {
			if (cave[row][col] == 'x' && !onAir[row][col]) {
				cave[row + minDrop][col] = 'x';
				cave[row][col] = '.';
			}
		}
	}
}

static int findMinDropDistance(int col) {
	int dropIdx = -1;
	int groundIdx = -1;
	boolean isDroppable = false;

	for (int row = rows - 1; row >= 0; row--) {
		if (cave[row][col] == 'x') {
			if (onAir[row][col]) {
				groundIdx = row;
			} else {
				if (groundIdx == -1) {
					dropIdx = row;
					groundIdx = rows - 1;
				} else {
					isDroppable = true;
					dropIdx = row;
				}
				break;
			}
		}
	}

	if (dropIdx == -1 || groundIdx == -1)
		return Integer.MAX_VALUE;
	return isDroppable ? groundIdx - dropIdx - 1 : groundIdx - dropIdx;
}

static void findConnectedMinerals(int row, int col) {
	for (int[] delta : directions) {
		int newRow = row + delta[0];
		int newCol = col + delta[1];
		if (isValid(newRow, newCol) && cave[newRow][newCol] == 'x' && !onAir[newRow][newCol]) {
			onAir[newRow][newCol] = true;
			findConnectedMinerals(newRow, newCol);
		}
	}
}

static boolean isValid(int row, int col) {
	return row >= 0 && row < rows && col >= 0 && col < cols;
}

출처:https://www.acmicpc.net/problem/2933