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, 3 , 0, 10 , 0, 20 , 1, 4 , 1, 7 , 1, 8 , 1, 10 , 1, 14 , 1, 21 , 2, 10 , 2, 14 , 2, 17 , 2, 21 , 2, 25 , 2, 29 , 3, 8 , 3, 12 , 3, 14 , 3, 25 , 4, 6 …