2024 day8

1 files changed, 34 insertions, 0 deletions

diff --git a/2024/day8/solve.py b/2024/day8/solve.py
new file mode 100644
index 0000000..9dba99e
--- /dev/null
+++ b/2024/day8/solve.py
@@ -0,0 +1,34 @@
+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]
+
+            pos1 = (antenna1[0] - row_diff, antenna1[1] - col_diff)
+            pos2 = (antenna2[0] + row_diff, antenna2[1] + col_diff)
+
+            if 0 <= pos1[0] < row_count and 0 <= pos1[1] < col_count:
+                antinodes.add(pos1)
+
+            if 0 <= pos2[0] < row_count and 0 <= pos2[1] < col_count:
+                antinodes.add(pos2)
+
+print(len(antinodes))
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