dynamic_programming_solver.py

def find_sets3(cards, indices=None):
    nd, n = cards.shape
    c0 = cards[0, :]
    if indices is None:
        indices = numpy.arange(n)

    groups = [(c0 == f).nonzero()[0] for f in range(nfeatures)]

    # equals
    solequal = []
    for g in groups:
        if len(g) < 3: continue
        solequal += find_sets3(cards[1:nd, g], indices[g])
    # different
    soldiff = [(indices[i0], indices[i1], indices[i2])
               for i0 in groups[0] for i1 in groups[1] for i2 in groups[2]
               if is_set(cards, (i0, i1, i2))]
    return solequal + soldiff