Python怎么实现贪婪排名算法？

results = {

#  'TEST': ( TIME, set([COVERED_POINT ...])),

 'test_00': ( 2.08, set([2, 3, 5, 11, 12, 16, 19, 23, 25, 26, 29, 36, 38, 40])),

 'test_01': ( 58.04, set([0, 10, 13, 15, 17, 19, 20, 22, 27, 30, 31, 33, 34])),

 'test_02': ( 34.82, set([3, 4, 6, 12, 15, 21, 23, 25, 26, 33, 34, 40])),

 'test_03': ( 32.74, set([4, 5, 10, 16, 21, 22, 26, 39])),

 'test_04': (100.00, set([0, 1, 4, 6, 7, 8, 9, 11, 12, 18, 26, 27, 31, 36])),

 'test_05': ( 4.46, set([1, 2, 6, 11, 14, 16, 17, 21, 22, 23, 30, 31])),

 'test_06': ( 69.57, set([10, 11, 15, 17, 19, 22, 26, 27, 30, 32, 38])),

 'test_07': ( 85.71, set([0, 2, 4, 5, 9, 10, 14, 17, 24, 34, 36, 39])),

 'test_08': ( 5.73, set([0, 3, 8, 9, 13, 19, 23, 25, 28, 36, 38])),

 'test_09': ( 15.55, set([7, 15, 17, 25, 26, 30, 31, 33, 36, 38, 39])),

 'test_10': ( 12.05, set([0, 4, 13, 14, 15, 24, 31, 35, 39])),

 'test_11': ( 52.23, set([0, 3, 6, 10, 11, 13, 23, 34, 40])),

 'test_12': ( 26.79, set([0, 1, 4, 5, 7, 8, 10, 12, 13, 31, 32, 40])),

 'test_13': ( 16.07, set([2, 6, 9, 11, 13, 15, 17, 18, 34])),

 'test_14': ( 40.62, set([1, 2, 8, 15, 16, 19, 22, 26, 29, 31, 33, 34, 38])),

 }

def greedyranker(results):

  results = results.copy()

  ranked, coveredsofar, costsofar, round = [], set(), 0, 0

  noncontributing = []

  while results:

    round += 1

    # What each test can contribute to the pool of what is covered so far

    contributions = [(len(cover - coveredsofar), -cost, test)

             for test, (cost, cover) in sorted(results.items()) ]

    # Greedy ranking by taking the next greatest contributor       

    delta_cover, benefit, test = max( contributions )

    if delta_cover > 0:

      ranked.append((test, delta_cover))

      cost, cover = results.pop(test)

      coveredsofar.update(cover)

      costsofar += cost

    for delta_cover, benefit, test in contributions:

      if delta_cover == 0:

        # this test cannot contribute anything

        noncontributing.append( (test, round) )

        results.pop(test)

  return coveredsofar, ranked, costsofar, noncontributing

def greedyranker(results, tutor=True):

  results = results.copy()

  ranked, coveredsofar, costsofar, round = [], set(), 0, 0

  noncontributing = []

  while results:

    round += 1

    # What each test can contribute to the pool of what is covered so far

    contributions = [(len(cover - coveredsofar), -cost, test)

             for test, (cost, cover) in sorted(results.items()) ]

    if tutor:

      print('\n## Round %i' % round)

      print(' Covered so far: %2i points: ' % len(coveredsofar))

      print(' Ranked so far: ' + repr([t for t, d in ranked]))

      print(' What the remaining tests can contribute, largest contributors first:')

      print('  # DELTA, BENEFIT, TEST')

      deltas = sorted(contributions, reverse=True)

      for delta_cover, benefit, test in deltas:

        print('   %2i,  %7.2f,  %s' % (delta_cover, benefit, test))

      if len(deltas)>=2 and deltas[0][0] == deltas[1][0]:

        print(' Note: This time around, more than one test gives the same')

        print('    maximum delta contribution of %i to the coverage so far'

            % deltas[0][0])

        if deltas[0][1] != deltas[1][1]:

          print('    we order based on the next field of minimum cost')

          print('    (equivalent to maximum negative cost).')

        else:

          print('    the next field of minimum cost is the same so')

          print('    we arbitrarily order by test name.')

      zeroes = [test for delta_cover, benefit, test in deltas

           if delta_cover == 0]

      if zeroes:

        print(' The following test(s) cannot contribute more to coverage')

        print(' and will be dropped:')

        print('  ' + ', '.join(zeroes))

    # Greedy ranking by taking the next greatest contributor       

    delta_cover, benefit, test = max( contributions )

    if delta_cover > 0:

      ranked.append((test, delta_cover))

      cost, cover = results.pop(test)

      if tutor:

        print(' Ranking %s in round %2i giving extra coverage of: %r'

            % (test, round, sorted(cover - coveredsofar)))

      coveredsofar.update(cover)

      costsofar += cost

    for delta_cover, benefit, test in contributions:

      if delta_cover == 0:

        # this test cannot contribute anything

        noncontributing.append( (test, round) )

        results.pop(test)

  if tutor:

    print('\n## ALL TESTS NOW RANKED OR DISCARDED\n')

  return coveredsofar, ranked, costsofar, noncontributing

totalcoverage, ranking, totalcost, nonranked = greedyranker(results)

print('''

A total of %i points were covered,

using only %i of the initial %i tests,

and should take %g time units to run.

The tests in order of coverage added:

  TEST DELTA-COVERAGE'''

 % (len(totalcoverage), len(ranking), len(results), totalcost))

print('\n'.join(' %6s %i' % r for r in ranking))