def one_correct_in_correct_place(x, y):
    if len([(i,j) for i,j in zip(x, y) if i==j]) == 1:
        return True

def one_correct_in_wrong_place(x, y):
    return n_correct_in_wrong_place(x, y, 1)

def two_correct_in_wrong_place(x, y):
    return n_correct_in_wrong_place(x, y, 2)

def n_correct_in_wrong_place(x, y, n):
    if any([(i==j) for i,j in zip(x, y)]):
        return

    if len([i for i,j in zip(x, y) if i in y]) == n:
        return True

def none_of(x, y):
    if any([i for i in x if i in y]):
        return
    return True

class Problem:
    def __init__(self, x):
        self.x = x
        self.constraints = []
        
    def add_constraint(self, y, *args):
        self.constraints.append( (y, args) )
        
    def get_solutions(self):
        solutions = self.x
        for constraint, args in self.constraints:
            solutions = [x for x in solutions if constraint(x, *args)]
        return solutions

if __name__ == '__main__':
    problem = Problem([(x,y,z) for x in range(10)
                       for y in range(10)
                       for z in range(10)])

    problem.add_constraint(one_correct_in_correct_place, (6, 8, 2))
    problem.add_constraint(one_correct_in_wrong_place, (6, 4, 5))
    problem.add_constraint(two_correct_in_wrong_place, (2, 0, 6))
    problem.add_constraint(none_of, (7, 3, 8))
    problem.add_constraint(one_correct_in_wrong_place, (7, 8, 0))

    solutions = problem.get_solutions()

    print('found %d solution(s)' % len(solutions))
    for solution in solutions:
        print("%d%d%d" % solution)