Hi Codeforces,

I've been working with AdhamAfterMidnight on a training group called Focused CPCs Training, and we've just added our third session: Binary Search on Answer.

The idea behind the group is to collect problems on a particular topic from different CPC contests, then arrange them by estimated difficulty. We wanted something we could use for our own training, and thought others might find it useful too.

So far, we have:

• Session 1 : Basics
• Session 2 : Adhocs
• Session 3 : Binary Search on Answer: 21 problems, specifically about binary searching the answer rather than ordinary binary search.

We're using the VoidHub CPC Archive to put these sessions together. The original contest collections are available there, while the group brings selected problems together by topic.

The archive includes contests such as ECPC, ACPC, Syrian CPCs, JCPC, KCPC and TCPC, alongside CERC, NWERC, SEERC, GCPC, BAPC, NCPC, UKIEPC, Ural, Dhaka, Jakarta, Azerbaijan and the North America Championship. Not all of these are represented in the group yet; we'll keep adding more sessions.

Each statement starts with “Originally from: [contest name]”, so the source is easy to find. These aren't our problems; credit goes to their original authors.

The group is private for now. Send a join request and I'll accept it.

Here's the group link. Give the sessions a try, and let us know if you find an issue or have a topic you'd like us to cover next.