groupStrings.py

# class Solution:
#     def groupStrings(self, strings: List[str]) -> List[List[str]]:
#         def shift_letter(letter, shift):
#             return chr((ord(letter) -shift)%26 + ord('a'))
        
#         def do_hash(string):
#             shift= ord(string[0])
#             return ''.join(shift_letter(letter, shift) for letter in string)
        
#         groups= collections.defaultdict(list)
#         for string in strings:
#             ret= do_hash(string)
#             groups[ret]=string
            
#         return list(groups.values())

class Solution:
    def groupStrings(self, strings: List[str]) -> List[List[str]]:
        
        def shift_letter(letter: str, shift: int):
            return chr((ord(letter) - shift) % 26 + ord('a'))
        
        # Create a hash value
        def get_hash(string: str):
            # Calculate the number of shifts to make the first character to be 'a'
            shift = ord(string[0])
            return ''.join(shift_letter(letter, shift) for letter in string)
        
        # Create a hash_value (hashKey) for each string and append the string
        # to the list of hash values i.e. mapHashToList["abc"] = ["abc", "bcd"]
        groups = collections.defaultdict(list)
        for string in strings:
            hash_key = get_hash(string)
            groups[hash_key].append(string)
        
        # Return a list of all of the grouped strings
        return list(groups.values())