Build options are officially allowed on C++ challenges. Our rules never covered this, and that's our mistake. The default build is C++23 with -O2 -march=native, and you may tune it from inside solution/: compile options and LTO via solution/libraries.cmake, and pragmas in your own sources. The benchmark and scoring stay fixed. Exploratory research is always welcome. Read the rules

New: Challenges Pro — a 1-minute wait between submissions and twice the daily limit. See what changes

Team members are back on the leaderboards. Joining a team no longer folds your entry into a single team row: leaderboards, rankings, and the badge wall now always show you individually, with a small team tag next to your name. Team-vs-team competition lives on at Team Standings. No action needed — if you'd left a team to stay visible, it's safe to rejoin.