2022 senior S3 Good Samples
constructive algorithm

2021 senior S3 Lunch Concert
binary search

2020 senior S3 searching for strings

two pointer
2019 senior S3 Arithmetic Square

2018 senior S3 robot theieves
BFS

2017 senior S3 Nailed it!

http://www.usaco.org/index.php?page=viewproblem2&cpid=739
enumeration

http://www.usaco.org/index.php?page=viewproblem2&cpid=941
weird problem