construct/nppc three coloring

construct/nppc three coloring: a task in MathConstructOptimize-Envs-harbor (Harbor dataset). Graph with 30 vertices labelled 0..29 and edge list 0, 1 , 0, 9 , 0, 10 , 0, 14 , 1, 7 , 1, 8 , 1, 12 , 1, 16 , 1, 25 , 1, 26 , 2, 19 , 2, 25 , 3, 12 , 3, 27 , 4, 10 , 4, 12 , 4, 21 , 5, 21 , 5, 22 , 6, 17…