More stuff

problemlist.md

@@ -112,3 +112,9 @@ A little collection of interesting problems that I randomly decided to do.
 	Not so hard if you know how to deal with C++ or any other language with big integer, but
 	it's interesting to think about regardless, can also be solved with a binary search, but
 	it's not required.
+
+## DSU
+
+- [https://codeforces.com/problemset/problem/1985/H1](https://codeforces.com/problemset/problem/1985/H1)
+
+	DSU with rollback problem, cool to think about and not really that difficult.