digit dp
Elaborate?
+1
Digit dp introduction:
GeeksforGeeks
USACO gold problem that uses this:
2021 February Contest, Gold: Count the Cows
This is late, but I wrote a book about DP (https://dp-book.com/) which has a detailed explanation of Digit DP in addition to the solution to Count the Cows, as coconut mentioned.
This can probably be added to the guide 
4 Likes
Sheesh… Where did you find time to write that? We should add this to the guide lol (p good ngl)…
It looks cool! 