08.py

from dataclasses import dataclass

@dataclass
class Location:
  frequency: str = None
  is_antinode: bool = False
  position: tuple = (-1, -1)
  def __repr__(self):
    if self.frequency is not None:
      return self.frequency
    if self.is_antinode:
      return '#'
    return '.'

map = []

with open('input.txt', 'r') as file:
  for y, line in enumerate(file):
    map_row = []
    for x, char in enumerate(line.strip()):
      location = Location()
      if char != '.':
        location.frequency = char
      location.position = (x, y)
      map_row.append(location)
    map.append(map_row)

antennas = []
for row in map:
  for location in row:
    if location.frequency is not None:
      antennas.append(location)

def get_line_equation(location1, location2):
  x1, y1 = location1.position
  x2, y2 = location2.position  
  if x1 == x2:
    return None
  m = (y2 - y1) / (x2 - x1)
  b = y1 - m * x1
  return m, b

def is_on_map(x, y):
  return x >= 0 and x < len(map[0]) and y >= 0 and y < len(map)

# Part 1

for antenna in antennas:
  for other_antenna in [other_antenna for other_antenna in antennas if other_antenna != antenna]:
    if antenna.frequency == other_antenna.frequency:
      line_equation = get_line_equation(antenna, other_antenna)
      antinode1_x = antinode1_y = antinode2_x = antinode2_y = None
      [x1, x2] = ([antenna.position[0], other_antenna.position[0]])
      x_diff = x2 - x1
      antinode1_x = x1 - x_diff
      antinode2_x = x2 + x_diff
      m, b = line_equation
      antinode1_y = round(m * antinode1_x + b)
      antinode2_y = round(m * antinode2_x + b)
      if is_on_map(antinode1_x, antinode1_y):
        map[antinode1_y][antinode1_x].is_antinode = True
      if is_on_map(antinode2_x, antinode2_y):
        map[int(antinode2_y)][antinode2_x].is_antinode = True

antinode_count = len([location for row in map for location in row if location.is_antinode])

print('Number of antinodes (part 1):', antinode_count)

# Part 2

for antenna in antennas:
  for other_antenna in [other_antenna for other_antenna in antennas if other_antenna != antenna]:
    if antenna.frequency == other_antenna.frequency:
      x_diff = abs(antenna.position[0] - other_antenna.position[0])
      line_equation = get_line_equation(antenna, other_antenna)
      x_values = (
        [x for x in range(antenna.position[0], -1, -x_diff)]
        + [x for x in range(antenna.position[0], len(map[0]), x_diff)]
      )
      for x in x_values:
        m, b = line_equation
        y = round(m * x + b)
        if is_on_map(x, y):
          map[y][x].is_antinode = True

antinode_count = len([location for row in map for location in row if location.is_antinode])

print('Number of antinodes (part 2):', antinode_count)