old_contents: # Time:  put:      O(1)
  #        retrieve: O(n + dlogd), n is the size of the total logs
  #                              , d is the size of the found logs
  # Space: O(n)
      
  class LogSystem(object):
  
      def __init__(self):
          self.__logs = []
          self.__granularity = {'Year': 5, 'Month': 8, 'Day': 11, \
                                'Hour': 14, 'Minute': 17, 'Second': 20}
          
  
      def put(self, id, timestamp):
          """
          :type id: int
          :type timestamp: str
          :rtype: void
          """
          self.__logs.append((id, timestamp))
  
          
      def retrieve(self, s, e, gra):
          """
          :type s: str
          :type e: str
          :type gra: str
          :rtype: List[int]
          """
          i = self.__granularity[gra]
          begin = s[:i]
          end = e[:i]
          return sorted(id for id, timestamp in self.__logs \
                        if begin <= timestamp[:i] <= end)
  
  
  # Your LogSystem object will be instantiated and called as such:
  # obj = LogSystem()
  # obj.put(id,timestamp)
  # param_2 = obj.retrieve(s,e,gra)
  
new_contents: # Time:  put:      O(1)
  #        retrieve: O(n + dlogd), n is the size of the total logs
  #                              , d is the size of the found logs
  # Space: O(n)
      
  class LogSystem(object):
  
      def __init__(self):
          self.__logs = []
          self.__granularity = {'Year': 4, 'Month': 7, 'Day': 10, \
                                'Hour': 13, 'Minute': 16, 'Second': 19}
          
  
      def put(self, id, timestamp):
          """
          :type id: int
          :type timestamp: str
          :rtype: void
          """
          self.__logs.append((id, timestamp))
  
          
      def retrieve(self, s, e, gra):
          """
          :type s: str
          :type e: str
          :type gra: str
          :rtype: List[int]
          """
          i = self.__granularity[gra]
          begin = s[:i]
          end = e[:i]
          return sorted(id for id, timestamp in self.__logs \
                        if begin <= timestamp[:i] <= end)
  
  
  # Your LogSystem object will be instantiated and called as such:
  # obj = LogSystem()
  # obj.put(id,timestamp)
  # param_2 = obj.retrieve(s,e,gra)
  
subject: Update design-log-storage-system.py