All challenges

Recover a rooted tree from antichain greedy black-box queries.

Decide graph connectivity through a hidden cut-neighborhood oracle.

Report the hidden line width from the RiOI editor source instance.

Find the singleton value through membership queries over a hidden shuffled multiset.

Estimate divisor counts for hidden integers through the original GCD query protocol.

Recover the hidden DiverC dictionary through the original autofill query service.

Count distinct bakery cake types in the source instance.

Recover a hidden circular disk by probing line-segment intersection lengths.

Find an adaptively hidden absent student despite bounded dishonest replies.

Identify all demagnetized magnets from the source instances.

Partition dangos into sticks containing one of each color.

Find the hidden chord in a cycle by querying shortest-path distances.