All challenges

Draw a square grid map whose color adjacencies exactly realize a country graph while minimizing K/N.

Draw a smaller colored map preserving ward adjacency relationships.

Select a small vertex cover for an undirected graph.

Explore a uniform directed cave by marking passages until the treasure appears.

Choose powered stations, cables, and radio strengths to cover residents at low cost.

Navigate hidden neighbor orders to visit every graph vertex efficiently.

Add derivable shortcuts to a path DAG so every ordered pair is reachable within three edges.

Identify hidden key and treasure stars through directed reachability questions.

Choose shuttle pads under budget to reduce travel distances between ship endpoints.

Choose rooted trees in a planar graph to maximize weighted depth attractiveness under a height limit.

Report which roads are repaired in the source road-network instance.

Give closed trail walks for ranger teams so every trail is inspected with balanced load.