[2024/12] add a comment in sides()

StarlitGhost · Dec 13, 2024 · 5c86edc · 5c86edc
1 parent c395ecd
commit 5c86edc
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/2024/12/script.py b/2024/12/script.py
@@ -28,6 +28,7 @@ def sides(region: set[tuple]) -> int:
     fences = defaultdict(list)
     for pos in region:
         for n, d in Dir.map_nswe(neighbours(pos)).items():
+            # no same-region neighbour in this direction, we found a fence
             if n not in region:
                 fences[d].append(pos)