From 56a15dff0a0ef1ed0c864e225e8c0d0c8c0dd8af Mon Sep 17 00:00:00 2001
From: Kees van Kempen <git@keesvankempen.nl>
Date: Sun, 29 Dec 2024 01:46:36 +0100
Subject: [PATCH] 2024(8): solve part 1

---
 2024/08/part1.py  | 51 +++++++++++++++++++++++++++++++++++++++++++++++
 2024/08/testinput | 12 +++++++++++
 2 files changed, 63 insertions(+)
 create mode 100644 2024/08/part1.py
 create mode 100644 2024/08/testinput

diff --git a/2024/08/part1.py b/2024/08/part1.py
new file mode 100644
index 0000000..bf754df
--- /dev/null
+++ b/2024/08/part1.py
@@ -0,0 +1,51 @@
+import numpy as np
+
+
+verbose = False
+
+def load_map(filename="input"):
+	"""
+	Reads a map from a file without verifying its contents.
+	"""
+
+	with open(filename, "r") as fp:
+		data = fp.read().splitlines()
+		chararray = np.array(data, dtype=str)\
+			.view("U1")\
+			.reshape((len(data), -1))
+	return chararray
+
+def isValid(shape: tuple, index: tuple):
+    for i in range(len(shape)):
+        if not (0 <= index[i] < shape[i]):
+            return False
+    return True
+
+if __name__ == "__main__":
+	m = load_map()
+	frequencies = np.unique(m)
+
+	antinodes = []
+
+	for f in frequencies:
+		# Emptiness is killing me.
+		if f == ".":
+			continue
+
+		# Find all antennas with the same frequency.
+		antennas = np.array(np.where(m == f)).T
+
+		# For each pair of antennas, find antinodes.
+		for i in range(len(antennas)):
+			for j in range(i + 1, len(antennas)):
+				a = antennas[i]
+				b = antennas[j]
+				
+				c = a + (a - b)
+				d = b + (b - a)
+				if isValid(m.shape, c):
+					antinodes.append(c)
+				if isValid(m.shape, d):
+					antinodes.append(d)
+
+	print(len(np.unique(antinodes,axis=0)))
diff --git a/2024/08/testinput b/2024/08/testinput
new file mode 100644
index 0000000..78a1e91
--- /dev/null
+++ b/2024/08/testinput
@@ -0,0 +1,12 @@
+............
+........0...
+.....0......
+.......0....
+....0.......
+......A.....
+............
+............
+........A...
+.........A..
+............
+............