Solve 2021 day 20, 21, 23, 25

README.md

@@ -191,7 +191,12 @@ Solutions and utility script for Advent of Code challenges in Python.
 - Day 17:  21:59   (Not tricky again but struggling for no reason.)
 - Day 18: 162:00   (I couldn't figure out how to solve it as a tree so I did the basic way.)
 - Day 19:
-- Day 20:
+- Day 20: 105:00   (That wasn't easy but was able to solve in one go.)
+- Day 21:  37:45   (Wasn't hard but I was just too slow.)
+- Day 22:
+- Day 23:  81:38   (Fun but obviously not competitive.)
+- Day 24:
+- Day 25:  15:43   (That could have been much much faster.)
 
 ## AoC 2022