void keyPressed() {
  int nextX = playerX;
  int nextY = playerY;

  if (keyCode == LEFT && maze[playerY / tileSize][(playerX - tileSize) / tileSize] != 1) {
    nextX -= tileSize;
  } else if (keyCode == RIGHT && maze[playerY / tileSize][(playerX + tileSize) / tileSize] != 1) {
    nextX += tileSize;
  } else if (keyCode == UP && maze[(playerY - tileSize) / tileSize][playerX / tileSize] != 1) {
    nextY -= tileSize;
  } else if (keyCode == DOWN && maze[(playerY + tileSize) / tileSize][playerX / tileSize] != 1) {
    nextY += tileSize;
  }

  if (nextX >= 0 && nextX < width && nextY >= 0 && nextY < height) {
    playerX = nextX;
    playerY = nextY;
  }
}