2024: Day 8

Author: MiLk

2024/python/day8/__init__.py

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+import math
+from itertools import combinations
+
+from black.trans import defaultdict
+
+from utils.file import read_input
+
+lines = read_input(__package__)
+
+height = len(lines)
+width = len(lines[0])
+
+expected: set[complex] = set()
+all_antennas: defaultdict[str, set[complex]] = defaultdict(set)
+for y, line in enumerate(lines):
+    for x, c in enumerate(line):
+        if c not in {".", "#"}:
+            all_antennas[c].add(complex(x, y))
+            expected.add(complex(x, y))
+        if c == "#":
+            expected.add(complex(x, y))
+
+antinodes: set[complex] = set()
+for frequency, antennas in all_antennas.items():
+    for a, b in combinations(antennas, 2):
+        diff = b - a
+        antinodes.add(a - diff)
+        antinodes.add(b + diff)
+
+valid_antinodes = {a for a in antinodes if 0 <= a.real < width and 0 <= a.imag < height}
+print("Part 1:", len(valid_antinodes))
+
+antinodes_p2 = valid_antinodes.copy() | {a for antennas in all_antennas.values() for a in antennas}
+for frequency, antennas in all_antennas.items():
+    for a, b in combinations(antennas, 2):
+        diff = b - a
+        candidates = set()
+        for i in range(1, min(width, height)):
+            candidates.add(a - i * diff)
+            candidates.add(b + i * diff)
+        for candidate in candidates:
+            if 0 <= candidate.real < width and 0 <= candidate.imag < height:
+                antinodes_p2.add(candidate)
+
+print("Part 2:", len(antinodes_p2))

2024/python/day8/__main__.py

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