message: Update possible-bipartition.py
diff: # - dislikes[i][0] < dislikes[i][1]
  # - There does not exist i != j for which dislikes[i] == dislikes[j].
  +import collections
  +
  +
  class Solution(object):
  def possibleBipartition(self, N, dislikes):
  """
  