Categorizing run time efficiency

Meredith implements a "graph coloring" algorithm, which comes up with colors for graph vertices such that no neighboring vertices share the same color.

The algorithm outputs graph colorings like this one:

Using a palette of just 3 colors, she runs the algorithm on graphs with varying amounts of vertices and records how long it takes.

Her findings are summarized in this table:

👁️Note that there are 2 answers to this question.