AoC 2024 day 8 part 1

aoc2024/src/day08/python/solution.py

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+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from typing import Sequence
+from collections import defaultdict
+
+_NO_ANTENNA = '.'
+
+# Antenas
+type Pos = tuple[int, int]
+
+def _find_antennas(city_map: Sequence[str]) -> dict[str, set[Pos]]:
+  """Finds antenna locations and groups them by frequency.
+  Frequency is represented by character, for example 'a'."""
+  antennas = defaultdict(set)
+  for y in range(len(city_map)):
+    for x in range(len(city_map[0])):
+      value = city_map[y][x]
+      if value != _NO_ANTENNA:
+        antennas[value].add((y, x))
+  return antennas
+
+
+def count_antinodes(city_map: Sequence[str]) -> int:
+  """Counts the antinodes resulting from antennas in the city."""
+  city_width = len(city_map[0])
+  city_height = len(city_map)
+  antennas: dict[chr, set[Pos]] = _find_antennas(city_map)
+  antinode_positions: set[Pos] = set()
+  for positions in antennas.values():
+    for curr_pos in positions:
+      for other_pos in positions:
+        if curr_pos == other_pos:
+          continue  # Skip same antenna.
+        distance = (other_pos[0] - curr_pos[0], other_pos[1] - curr_pos[1])
+        antinode_pos = (other_pos[0] + distance[0], other_pos[1] + distance[1])
+        if 0 <= antinode_pos[0] < city_height and 0 <= antinode_pos[1] < city_width:
+          # Antinode is within city bounds
+          antinode_positions.add(antinode_pos)
+  return len(antinode_positions)

aoc2024/test/day08/python/example1.txt

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+............
+........0...
+.....0......
+.......0....
+....0.......
+......A.....
+............
+............
+........A...
+.........A..
+............
+............

aoc2024/test/day08/python/input.txt

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+.....wV....q.....................................n
+.......w......q.h.....Vn.........................D
+............w.S..G.....................DT.........
+......S........h......e..T.....y......D...........
+......m.......Ae.......T........o.................
+....m....S........................................
+...m..........................n........8..........
+.........2...G......................n.............
+..2........V.......h................Q.............
+............................o.....................
+.Z......I..U....e...u.....G....o..................
+...N..G.........................................y.
+.....I............q.......h...................s...
+......U........qI....o.V..Rz........8........k....
+......d.Z.........................R.......8y......
+.........e..............T.....l...................
+.......2.........................u...R............
+.....d.............................Q..............
+...................v.....................s.Q....M.
+........2..........4.....................8..7.k...
+...........x..N..................A..........k.....
+...........ZN...........v...............K.........
+...d.......N.....................Ky.6.............
+...........................l6.....................
+....L....g.................4.......k..K.......0...
+..............L...........4R................s.....
+U......r..............H.4.........................
+.......U.............a.......H.............u......
+......xY...............l..........................
+...................................6..u...........
+........Y......L......l............0..............
+......9..L...........A.....v..HEa........K........
+..................v........6.EX.............z.....
+d..Y.............m......A.........................
+......................a.i......M...........z......
+...................g.......................0......
+...............................H.........i........
+..........3................W........E...i...0.....
+.................t.a....g.................5.......
+.r...t...........................7.....5..........
+....................................7....5........
+....................g.Y...wMz.....................
+9..........O....3................W.7..E..XD...1...
+t..............3.x.....9..........W.M.............
+...9............W.................................
+Z.............x................X.i......5.........
+...........3.....................................1
+...................O.......s....X.................
+..............r...................................
+..........................O.................1.....

aoc2024/test/day08/python/test_solution.py

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+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import unittest
+
+from common.python3.AdventOfCodeTestCase import AdventOfCodeTestCase
+from aoc2024.src.day08.python.solution import count_antinodes
+
+
+class TestDay08Solution(AdventOfCodeTestCase):
+  def __init__(self, *args, **kwargs):
+    (super(TestDay08Solution, self).__init__(__file__, *args, **kwargs))
+
+  def test_part1_withExample_counts(self):
+    self.assertEqual(14, count_antinodes(self.examples[0]))
+
+  def test_part1_withPuzzleInput_counts(self):
+    self.assertEqual(327, count_antinodes(self.input))
+
+
+if __name__ == '__main__':
+  unittest.main()