construct/nppc three coloring

construct/nppc three coloring: a task in MathConstructOptimize-Envs-harbor (Harbor dataset). Graph with 60 vertices labelled 0..59 and edge list 0, 4 , 0, 44 , 0, 58 , 1, 3 , 1, 6 , 1, 9 , 1, 26 , 1, 55 , 2, 11 , 2, 29 , 2, 37 , 2, 47 , 2, 50 , 2, 55 , 3, 28 , 3, 41 , 3, 42 , 3, 47 , 3, 50 , 3, 53…