code: private static TreeMap<Double ,Set<String>> sortScoreMap(TreeMap<String, Double> scoreMap)
      {
          TreeMap<Double, Set<String>> result = new TreeMap<Double, Set<String>>(Collections.reverseOrder());
          for (Map.Entry<String, Double> entry : scoreMap.entrySet())
          {
              Set<String> sentenceSet = result.get(entry.getValue());
              if (sentenceSet == null)
              {
                  sentenceSet = new HashSet<String>();
                  result.put(entry.getValue(), sentenceSet);
              }
              sentenceSet.add(entry.getKey());
          }
  
          return result;
      }
docs: 将分数map排序折叠
  @param scoreMap
  @return