blob: 1642e35d87e31247753e991223b495af86c1a8fa (
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lines = []
with open("input") as f:
for line in f:
lines.append(line.strip())
antennas: dict[str, list[tuple[int, int]]] = {}
for row_idx, line in enumerate(lines):
for col_idx, char in enumerate(line):
if char != ".":
if char not in antennas:
antennas[char] = []
antennas[char].append((row_idx, col_idx))
row_count = len(lines)
col_count = len(lines[0])
antinodes: set[tuple[int, int]] = set()
for antenna_list in antennas.values():
for idx, antenna1 in enumerate(antenna_list):
for antenna2 in antenna_list[idx + 1:]:
row_diff = antenna2[0] - antenna1[0]
col_diff = antenna2[1] - antenna1[1]
pos = antenna1
while 0 <= pos[0] < row_count and 0 <= pos[1] < col_count:
antinodes.add(pos)
pos = (pos[0] - row_diff, pos[1] - col_diff)
pos = antenna2
while 0 <= pos[0] < row_count and 0 <= pos[1] < col_count:
antinodes.add(pos)
pos = (pos[0] + row_diff, pos[1] + col_diff)
print(len(antinodes))
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