Day 9: helper docstring

ephemient · ephemient · commit 93e98dd6fbb7 · 2025-01-09T23:32:01.000-05:00
diff --git a/py/aoc2024/day9.py b/py/aoc2024/day9.py
@@ -10,6 +10,9 @@
 
 
 def _rangesum(start: int, size: int) -> int:
+    """
+    _rangesum(start, size) == sum(range(start, start + size))
+    """
     return (2 * start + size - 1) * size // 2
 
 
