https://www.pramp.com/challenge/AMypWAprdmUlaP2gPVLZ

Flatten-a-Dictionary.py

# Time: O(N) where N is the number of keys in the input dictionary 
# Space: O(N) since the ouput dict is asymptotically as big as the input dict

def flatten_dictionary(dictionary):
  pass # your code goes here
  flat_dict = {}
  flat_dict_helper("", dictionary, flat_dict)
  return flat_dict

def flat_dict_helper(inital_key, dictionary, flat_dict):
  for key in dictionary.keys():
    val = dictionary.get(key)
    
    if not isinstance(val, dict):
      if inital_key == None or inital_key == "":
        flat_dict[key] = val
      else:
        flat_dict[inital_key + "." + key] = val 
    else:
      if inital_key == None or inital_key == "":
        flat_dict_helper(key, val, flat_dict)
      else:
        flat_dict_helper(inital_key + "." + key, val, flat_dict_helper)
    
    
dictionary = {
            "Key1" : "1",
            "Key2" : {
                "a" : "2",
                "b" : "3",
                "c" : {
                    "d" : "3",
                    "e" : {
                        "" : "1"
                    }
                }
            }
        }



print flatten_dictionary(dictionary)