Add custom range sum function to speed things up a bit

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

day07/day07.py

@@ -3,6 +3,10 @@ import sys
 from typing import Sequence
 
 
+def rangesum(rn: range):
+    return (((rn.stop + 1) * rn.stop) // 2) - (((rn.start + 1) * rn.start) // 2)
+
+
 def part1(positions: Sequence[int]):
     lo = min(positions)
     hi = max(positions)
@@ -15,10 +19,10 @@ def part1(positions: Sequence[int]):
 def part2(positions: Sequence[int]):
     lo = min(positions)
     hi = max(positions)
-    diffs = []
+    ranges = []
     for i in range(lo, hi + 1):
-        diffs += [sum(sum(range(abs(pos - i) + 1)) for pos in positions)]
-
+        ranges += [[range(abs(pos - i)) for pos in positions]]
+    diffs = [sum(rangesum(r) for r in rs) for rs in ranges]
     print(min(diffs))