construct/nppc three coloring

construct/nppc three coloring: a task in MathConstructOptimize-Envs-harbor (Harbor dataset). Graph with 15 vertices labelled 0..14 and edge list 0, 4 , 0, 8 , 0, 10 , 0, 11 , 0, 12 , 0, 14 , 1, 3 , 1, 7 , 1, 8 , 1, 11 , 2, 4 , 2, 7 , 2, 9 , 2, 10 , 2, 11 , 2, 12 , 2, 14 , 3, 4 , 3, 9 , 3, 11 , 3…