How to take part in a tournament

Step 1: Sign in with your CodeKairo account

Open battles.codekairo.com and choose Sign in. Battles has no accounts of its own: the CodeKairo account you practise with works here, and an account made here works on codekairo.com too.

If you are already signed in on codekairo.com, Battles usually recognises you on your first visit.

On the screen

1. Participant — the door only decides where you land after signing in: the tournaments list.
2. Your CodeKairo email and password.
3. Or continue with Google or GitHub.

New here? Create an account from the same page, with email, Google or GitHub. It is free.

Step 2: Find a tournament

Tournaments in the bar opens the list: every published tournament of a verified college, club or company that has not finished. Each row gives the organizer, the format, the start and the places taken.

Your organizer may also send you the tournament's link directly.

On the screen

1. Your own tournaments, with the status of your entry, once you have entered one.
2. Everything open or coming up, soonest first.
3. Where each one stands: registration open, registration closed, or live.

Step 3: Read the rules and register

The tournament page lists the format, the start, the length of each match or of the contest, when registration closes, how many problems there are — they stay hidden until the start — and the places taken.

The Registration panel says who may enter. Register before registration closes. If the organizer approves each entry, you will see Waiting for approval until they do.

On the screen

1. The facts: format, times, problem count and places.
2. Who may enter — an email domain, an invite code, the organizer's approval, or anyone.
3. The invite code, when the tournament asks for one.
4. Register. Your status replaces the button: Registered, or Waiting for approval.

An ICPC-style contest has no Register button: the organizer enters every team. Ask them to add yours, then sign in with the email or username they listed.

Step 4: Check in during the hour before a knockout

A knockout seeds only the players who turn up. Check-in opens 60 minutes before the start and closes at the start; the button appears on the tournament page by itself.

Once you have checked in, keep the page open: at the start the bracket is drawn — by CodeKairo rating — and your first match appears here.

On the screen

1. Your entry's status.
2. Check in — it appears when the window opens. Miss it and you are not seeded.

Step 5: Play your match

Go to your match opens the match room: you, your opponent and one problem on a clock. The first accepted solution wins the match on the spot.

Write your solution in any of the 13 languages. Run checks the sample cases; Submit judges the hidden tests. If time runs out, the player who passed more hidden tests wins — then whoever got there first, then the better seed.

On the screen

1. The round, and the time left.
2. You and your opponent, each with the best number of hidden tests passed so far.
3. The problem, and the editor with the language, Run and Submit.
4. Results: each sample case, then the verdict of a submission.

Won? Your next match starts a minute after your next opponent is known. The Bracket button shows where you stand.

Step 6: In an ICPC-style contest, work as a team

Your team's room opens at the start with the whole problem set. Every member signs in with their own account and can submit; a solved problem gets a tick on its tab.

The board ranks by problems solved, then by penalty time: the minute of each first accepted solution plus 20 for every rejected attempt before it. A compile error costs nothing.

On the screen

1. The contest, your team and the clock.
2. One tab per problem — A, B, C … — ticked once your team solves it, then your team's submissions with their verdicts.
3. The scoreboard, public from the start.

Step 7: Follow the scoreboard or the bracket

The scoreboard refreshes every 15 seconds while the contest runs. If the organizer froze it for the last stretch, other teams' attempts show as ? until the results are revealed after the end.

A knockout has a bracket instead, filled in round by round as matches are decided.

On the screen

1. Solved, with the attempts it took.
2. An attempt made during the freeze, shown as pending.
3. Problems solved and penalty minutes decide the rank.

Step 8: Keep what you solved

Every accepted solution in a tournament is an ordinary CodeKairo submission. It counts toward your solved problems, heatmap, streak and roadmap stages, and pays XP the first time you solve that problem.

On codekairo.com the problem carries a solved-in-a-tournament trophy, and your profile's Tournaments section lists every tournament you played with where you finished.

On the screen

1. Every tournament you played, with your placement.
2. A problem you solved in a tournament, marked with the trophy.