December 8th (#7)

Author: plbrault

08.py

@@ -0,0 +1,88 @@
+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)