exhaustive n<=6 graphs: 33867 fails 0 worst by r {1: 0, 2: 2, 3: 3, 4: 2, 5: 1} #exceed 2r-2: 0
random n=7..11: fails 0 worst by r {2: 2, 3: 4, 4: 6, 5: 6, 6: 5, 7: 4, 8: 3} #exceed 2r-2: 0
