[mypy] Fix type annotations for strings (#4637)

* Fix mypy error for can_string_be_rearranged_as_pal

* Fix mypy error for levenshtein_distance.py

* Fix mypy error for word_patterns.py

* Fix mypy error for word_occurrence.py

strings/can_string_be_rearranged_as_palindrome.py

@@ -43,7 +43,7 @@ def can_string_be_rearranged_as_palindrome(input_str: str = "") -> bool:
         return True
     lower_case_input_str = input_str.replace(" ", "").lower()
     # character_freq_dict: Stores the frequency of every character in the input string
-    character_freq_dict = {}
+    character_freq_dict: dict[str, int] = {}
 
     for character in lower_case_input_str:
         character_freq_dict[character] = character_freq_dict.get(character, 0) + 1

strings/levenshtein_distance.py

@@ -41,7 +41,7 @@ def levenshtein_distance(first_word: str, second_word: str) -> int:
     if len(second_word) == 0:
         return len(first_word)
 
-    previous_row = range(len(second_word) + 1)
+    previous_row = list(range(len(second_word) + 1))
 
     for i, c1 in enumerate(first_word):
 

strings/word_occurrence.py

@@ -14,7 +14,7 @@ def word_occurence(sentence: str) -> dict:
     >>> dict(word_occurence("Two  spaces"))
     {'Two': 1, 'spaces': 1}
     """
-    occurrence = defaultdict(int)
+    occurrence: dict = defaultdict(int)
     # Creating a dictionary containing count of each word
     for word in sentence.split():
         occurrence[word] += 1

strings/word_patterns.py

@@ -28,7 +28,7 @@ if __name__ == "__main__":
     with open("dictionary.txt") as in_file:
         wordList = in_file.read().splitlines()
 
-    all_patterns = {}
+    all_patterns: dict = {}
     for word in wordList:
         pattern = get_word_pattern(word)
         if pattern in all_patterns: