day20: comment to clarify the == 4

2020-12-20 20:23:26 +01:00 · 2020-12-20 20:23:26 +01:00 · 4c9e7f2838
commit 4c9e7f2838
parent 961fc2a8cb
1 changed files with 1 additions and 1 deletions
--- a/day20.py
+++ b/day20.py
@ -81,7 +81,7 @@ def getCornerPieces(tile_dict, only_get_first_piece=False):
        for border in tile.getPossibleBorderList():
            single_borders += all_borders.count(border) - 1

-        if single_borders == 4:
+        if single_borders == 4:  # every border shows up twice (1x straight, 1x reversed)
            if only_get_first_piece:
                return tile_id
            corner_pieces.append(tile_id)