[2024/8] comments and tidying

2024/8/script.py

@@ -2,50 +2,64 @@
 from GhostyUtils.grid import Grid
 from GhostyUtils.vec2 import Vec2
 from itertools import combinations
-import math
 
 
-def antinodes(a: tuple, b: tuple, grid: Grid, resonates: bool = False) -> list[tuple]:
+# calculates and returns a list of antinode positions from a pair of antenna
+def calc_antinodes(a: tuple, b: tuple, grid: Grid, resonates: bool = False) -> list[tuple]:
     a, b = Vec2(a), Vec2(b)
-    v = b - a
+    v = b - a  # vector between a & b
     # print(f"a: {a} b: {b} v: {v} | {a - v} {b + v}")
+
     nodes = []
+
+    # p1
     if not resonates:
-        aa = (a - v).as_tuple()
-        ab = (b + v).as_tuple()
+        aa = (a - v).as_tuple()  # project v back from a
+        ab = (b + v).as_tuple()  # project v forward from b
         nodes += [aa] if grid.in_bounds(aa) else []
         nodes += [ab] if grid.in_bounds(ab) else []
+
+    # p2
     else:
+        # add the antenna positions themselves
         nodes += [a.as_tuple(), b.as_tuple()]
+
+        # repeatedly project v back from a until we go out of bounds
         pos = a - v
         while grid.in_bounds(pos):
             nodes += [pos.as_tuple()]
             pos -= v
+
+        # repeatedly project v forward from b until we go out of bounds
         pos = b + v
         while grid.in_bounds(pos):
             nodes += [pos.as_tuple()]
             pos += v
+
     return nodes
 
 
 def main():
     grid = Grid(aoc.read_lines())
     antennas = {}
 
-    for element, pos in grid.by_cell():
-        if element != '.':
-            antennas.setdefault(element, []).append(pos)
+    # find all the antennas, and store them as {frequency: [positions]}
+    for freq, pos in grid.by_cell():
+        if freq != '.':
+            antennas.setdefault(freq, []).append(pos)
 
     antinode_positions = set()
+
+    # calculate antinodes for each antenna frequency
     for antenna, positions in antennas.items():
         for combo in combinations(positions, 2):
-            antinode_positions.update(antinodes(*combo, grid))
-
+            antinode_positions.update(calc_antinodes(*combo, grid))
     print(f"p1: {len(antinode_positions)}")
 
+    # calculate antinodes for each antenna frequency, with resonance
     for antenna, positions in antennas.items():
         for combo in combinations(positions, 2):
-            antinode_positions.update(antinodes(*combo, grid, resonates=True))
+            antinode_positions.update(calc_antinodes(*combo, grid, resonates=True))
     print(f"p2: {len(antinode_positions)}")