Day 8 part 2 success

Author: tauroid

2024/day_08/Python/antinodes.py

@@ -1,20 +1,25 @@
+from fractions import Fraction
 import string
 from itertools import combinations
 import numpy as np
 
 
+def array_from_lines(lines):
+    new_lines = []
+    for line in lines:
+        new_lines.append(np.array(list(line.strip())))
+
+    return np.array(new_lines)
+
+
 def load_input(filename):
     """
     Load the puzzle input from a file.
     """
     with open(filename, "r") as file:
         lines = file.readlines()
 
-    new_lines = []
-    for line in lines:
-        new_lines.append(np.array(list(line.strip())))
-
-    return np.array(new_lines)
+    return array_from_lines(lines)
 
 
 def find_antennae(puzzle_input, freq):
@@ -37,9 +42,17 @@ def find_antinodes(coordinateA, coordinateB):
     return antinodeA, antinodeB
 
 
-if __name__ == "__main__":
-    puzzle_input = load_input("input.txt")
+def find_antinodes_part_2(coordinateA, coordinateB):
+    diff = coordinateA - coordinateB
+    fr = Fraction(*diff)
+    diff_simplified = np.array([fr.numerator, fr.denominator])
 
+    for i in range(100):
+        yield coordinateA + i * diff_simplified
+        yield coordinateA - i * diff_simplified
+
+
+def find_antinodes_from_antennas(find_antinodes_fn, puzzle_input):
     puzzle_bounds = np.array(puzzle_input).shape
 
     frequencies = string.digits + string.ascii_lowercase + string.ascii_uppercase
@@ -51,17 +64,40 @@ def find_antinodes(coordinateA, coordinateB):
 
         # Find antinodes
         for antenna in combinations(antennae, 2):
-            antinodes.extend(find_antinodes(antenna[0], antenna[1]))
+            antinodes.extend(find_antinodes_fn(antenna[0], antenna[1]))
 
     antinodes = set(map(tuple, antinodes))
-    print(antinodes)
 
     # Remove out of bounds
     antinodes = [
         antinode
         for antinode in antinodes
         if all(0 <= coord < bound for coord, bound in zip(antinode, puzzle_bounds))
     ]
+
+    puzzle_grid = np.array(puzzle_input)
+    for antinode in antinodes:
+        if puzzle_grid[antinode] == ".":
+            puzzle_grid[antinode] = "#"
+
+    row_strs = []
+    for row in puzzle_grid:
+        row_strs.append("".join(row))
+
+    puzzle_grid_str = "\n".join(row_strs)
+
+    print(puzzle_grid_str)
+
     print(len(antinodes))
 
+    return puzzle_grid_str
+
+
+if __name__ == "__main__":
+    puzzle_input = load_input("input.txt")
+
+    find_antinodes_from_antennas(find_antinodes, puzzle_input)
+
     # Part 2 here
+
+    find_antinodes_from_antennas(find_antinodes_part_2, puzzle_input)

2024/day_08/Python/test_antinodes.py

@@ -0,0 +1,37 @@
+import inspect
+from antinodes import (
+    array_from_lines,
+    find_antinodes_from_antennas,
+    find_antinodes_part_2,
+)
+
+
+def test_antinodes_part_2():
+    grid = inspect.cleandoc(
+        """
+        .......
+        .......
+        ....A..
+        .......
+        ..A....
+        .......
+        .......
+        """
+    ).strip()
+
+    assert (
+        inspect.cleandoc(
+            """
+            ......#
+            .....#.
+            ....A..
+            ...#...
+            ..A....
+            .#.....
+            #......
+            """
+        ).strip()
+        == find_antinodes_from_antennas(
+            find_antinodes_part_2, array_from_lines(grid.split("\n"))
+        )
+    )