The Algorithm Design Manual

basis cases, namely the specification of the smallest and simplest objects where the decomposition stops.

Subsets are likely the object in question whenever your problem seeks a “cluster,” “collection,” “committee,” “group,” “packaging,” or “selection.”

Points are likely the object in question whenever your problems work on “sites,” “positions,” “data records,” or “locations.”

Permutations are likely the object in question whenever your problem seeks an “arrangement,” “tour,” “ordering,” or “sequence.”

Graphs are likely the object in question whenever you seek a “network,” “circuit,” “web,” or “relationship.”

Strings are likely the object in question whenever you are dealing with “text,” “characters,” “patterns,” or “labels.”

Learning to think recursively is learning to look for big things that are made from smaller things of exactly the same type as the big thing.

Order does not matter in subsets

Polygons and polyhedra are likely the object in question whenever you are working on “shapes,” “regions,” “configurations,” or “boundaries.”