241225 뱀

private static final int WALL = -1;
private static final int APPLE = 1;
private static final int EMPTY = 0;
private static final int LEFT_TURN = 3;
private static final int RIGHT_TURN = 1;
private static final int MAX_TIME = 10_100;
private static final char LEFT = 'L';

public static void main(String[] args) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	int boardSize = Integer.parseInt(br.readLine());
	int appleCount = Integer.parseInt(br.readLine());

	int[][] board = initializeBoard(boardSize, appleCount, br);
	int directionChanges = Integer.parseInt(br.readLine());
	int[][] moves = getMoves(directionChanges, br);

	int result = simulateGame(board, moves);
	System.out.print(result);
}

private static int[][] initializeBoard(int n, int k, BufferedReader br) throws IOException {
	int size = n + 2;
	int[][] board = new int[size][size];

	for (int i = 0; i < size; i++) {
		board[0][i] = WALL;
		board[size - 1][i] = WALL;
		board[i][0] = WALL;
		board[i][size - 1] = WALL;
	}

	for (int i = 0; i < k; i++) {
		StringTokenizer st = new StringTokenizer(br.readLine());
		int row = Integer.parseInt(st.nextToken());
		int col = Integer.parseInt(st.nextToken());
		board[row][col] = APPLE;
	}
	return board;
}

private static int[][] getMoves(int l, BufferedReader br) throws IOException {
	int[][] moves = new int[l][2];
	for (int i = 0; i < l; i++) {
		StringTokenizer st = new StringTokenizer(br.readLine());
		moves[i][0] = Integer.parseInt(st.nextToken());
		moves[i][1] = st.nextToken().charAt(0) == LEFT ? LEFT_TURN : RIGHT_TURN;
	}
	return moves;
}

private static int simulateGame(int[][] board, int[][] moves) {
	int[] dx = { -1, 0, 1, 0 };
	int[] dy = { 0, 1, 0, -1 };
	int direction = 1;
	int time = 0;
	int x = 1, y = 1;
	int moveIndex = 0;
	int snakeLength = 1;
	int[][] snake = new int[MAX_TIME][2];
	snake[0][0] = x;
	snake[0][1] = y;
	board[x][y] = WALL;

	while (true) {
		time++;
		x += dx[direction];
		y += dy[direction];

		if (board[x][y] == WALL)
			break;

		if (board[x][y] == APPLE) {
			snakeLength++;
		} else {
			int tailX = snake[time - snakeLength][0];
			int tailY = snake[time - snakeLength][1];
			board[tailX][tailY] = EMPTY;
		}

		board[x][y] = WALL;
		snake[time][0] = x;
		snake[time][1] = y;

		if (moveIndex < moves.length && moves[moveIndex][0] == time) {
			direction = (direction + moves[moveIndex][1]) % 4;
			moveIndex++;
		}
	}
	return time;
}

출처:https://www.acmicpc.net/problem/3190