Non-linear ADTs—Graphs

Abstract

In chapter 3 we introduced linear data types as a collection of objects where each object, in general, could have one ‘next’ object and one ‘previous’ object. Trees were non-linear data types where the above restriction was relaxed and each object could have more than one ‘next’ object (children of a node) but, at most, only one ‘previous’ object (parent of a node). We can further generalise tree structures by allowing an object to have more than one ‘previous’ object. A graph is such an unconstrained structure where each object may have zero, one or many ‘next’ and ‘previous’ objects. This generality obviously adds an extra degree of freedom in structuring data to relate to the structure of real-world situations.