I recently got into USACO platinum division and would like to try out lots of high quality problems. So far, I've completed USACO 2011 to 2019 Gold/Platinum problems.

Newer USACO Problems (2011+ ) Problem & Editorials http://www.usaco.org/index.php?page=contests ( 2011 onwards )

Now, I'm not sure what other problem sets to try. I've compiled possible candidates but want community opinion on quality of the problems from the list to optimize for learning. (Or suggest some other problem lists that i've missed)

a) Old USACO problems 2004 to 2011 Problems: http://tjsct.wikidot.com/usaco. (2007 to 2011) Editorials (Change Year # for other years) https://contest.usaco.org/OCT04.htm https://contest.usaco.org/OCT10.htm https://contest.usaco.org/NOV04.htm https://contest.usaco.org/NOV10.htm https://contest.usaco.org/DEC04.htm https://contest.usaco.org/DEC10.htm https://contest.usaco.org/JAN05.htm https://contest.usaco.org/JAN11.htm https://contest.usaco.org/FEB05.htm https://contest.usaco.org/FEB11.htm https://contest.usaco.org/MAR05.htm https://contest.usaco.org/MAR11.htm https://contest.usaco.org/OPEN05.htm https://contest.usaco.org/OPEN11.htm

b) Old IOI problems https://wcipeg.com/problems

c) Problems from Competitive Programming Handbook https://cses.fi/problemset/

d) Croation IOI https://hsin.hr/coci/

e) CP 3 ProblemSet https://cpbook.net/methodstosolve

Thanks