def subset_to_str_list(subset_sol):
    """From a subset solution (e.g.: [[0,1],[0,0]]) returns a list with the rows string and the columns string (e.g.: ['0 1', '0 0']) or NO_SOL"""
    return [' '.join([str(e) for e in subset_sol[0]]), \
            ' '.join([str(e) for e in subset_sol[1]])]