IOI 2027 in Potsdam: a guide for families

1. The Bundeswettbewerb Informatik. Entering it is a requirement, BWINF's FAQ says. Finalists and other very strong round 2 entrants are invited to the IOI selection if they meet the IOI's rules.
2. Online pre-selection. For the 2027 team it began on 5 September 2026 with 72 participants, invited from the 44th Bundeswettbewerb. Training runs online on Saturdays, with about 15 coaches, all former participants, each pupil with a personal coach. The language is C++.
3. Two qualification contests in November. They decide who is invited to the in-person selection.
4. Selection camps. BWINF's pages describe three Lehrgänge, each with two selection contests, together with talks on algorithms and problem-solving strategies. After the second camp about six or seven pupils go on to the third.
5. The team of four. Places in the selection contests decide the teams for the Baltic, Central European and International olympiads.

Sources: BWINF, Informatik-Olympiaden 2027, Teilnehmen and FAQ pages, and BWINF news of 2026, which names the 45th Bundeswettbewerb as the way into the selection for the IOI 2028 in Japan. Read on 3 November 2026. The second row's timing is our reading of the yearly pattern.

The table carries the most important fact on this page for families. The selection for Potsdam is already under way, among pupils who did well in the 44th Bundeswettbewerb. A teenager who starts serious preparation today is preparing for the 45th Bundeswettbewerb, whose first round closes on 23 November 2026, and through it for later olympiads. The same selection contests also decide Germany's teams for the Baltic and Central European olympiads; BWINF lists the 33rd Baltic Olympiad in Informatics for 14 to 18 April 2027 in Bergen, Norway.

import random

def brute(a):
    longest = 0
    for i in range(len(a)):
        for j in range(i, len(a)):
            if all(a[k] < a[k + 1] for k in range(i, j)):
                longest = max(longest, j - i + 1)
    return longest

def fast_first_try(a):
    longest, run = 1, 1
    for i in range(1, len(a)):
        if a[i] > a[i - 1]:
            run += 1
        else:
            longest = max(longest, run)
            run = 1
    return longest

def fast(a):
    longest, run = 1, 1
    for i in range(1, len(a)):
        run = run + 1 if a[i] > a[i - 1] else 1
        longest = max(longest, run)
    return longest

def stress(candidate, tests=1000):
    random.seed(2027)
    for t in range(tests):
        a = [random.randint(1, 5) for _ in range(random.randint(1, 6))]
        if candidate(a) != brute(a):
            return "test " + str(t) + " fails on " + str(a) + ": got " + str(candidate(a)) + ", expected " + str(brute(a))
    return "all " + str(tests) + " tests agree"

print("first try:", stress(fast_first_try))
print("fixed:", stress(fast))

The first try looks reasonable and passes the example 3, 5, 7, 2, 8. Its bug only shows when the longest run is at the very end of the list: it updates the longest run found so far only when a run breaks, so a run that is still going when the list ends is never counted. On [4, 4, 2, 4] the final run 2, 4 has length 2, and the first try answers 1. The fix updates that record at every step. The random tester found the bug on its seventh list, in a fraction of a second; a grader with hidden data would have found it too, and taken the points.

1. Reproduce it. Run the code. Then trace fast_first_try on [4, 4, 2, 4] by hand and find the moment it goes wrong.
2. Break it again. Change the fixed version so the run continues when two counts are equal. Does the stress test catch your new bug, and on which list?
3. Port it. Write the brute force and the fixed solution in C++, the language of BWINF's pre-selection, and compare them with the same random lists.
4. Going further. Change the generator to produce lists of length 1. Which of the three functions has a problem with an empty list, and should the task allow one?

Germany's time is set by the Einheitenzeitgesetz: UTC+1 in winter, UTC+2 in summer. Clocks went back on 25 October 2026 and go forward on 28 March 2027. India uses UTC+5:30 throughout, which puts it 4 hours 30 minutes ahead in winter and 3 hours 30 minutes in summer.

Group classes keep the slot their members agreed; one-to-one pupils often add a session before a contest deadline. Choose the trial lesson in whatever clock you live by.