diff --git a/python3/1/a.py b/python3/1/a.py
index 3a581bb..6c5936e 100644
--- a/python3/1/a.py
+++ b/python3/1/a.py
@@ -5,8 +5,10 @@
 
 class Solution:
     def twoSum(self, nums: list[int], target: int) -> list[int]:
-        n = len(nums)
+        n: int = len(nums)
 
+        i: int
+        j: int
         # enumerate does not allow the last item to be skipped without slicing,
         # which would require linear auxiliary space.
         for i in range(n - 1):
diff --git a/python3/1/b.py b/python3/1/b.py
index cbfcbb2..6391235 100644
--- a/python3/1/b.py
+++ b/python3/1/b.py
@@ -5,10 +5,12 @@
 
 class Solution:
     def twoSum(self, nums: list[int], target: int) -> list[int]:
-        i = 0
-        j = len(nums) - 1
-        snums = sorted(nums)
+        snums: list[int] = sorted(nums)
 
+        i: int = 0
+        j: int = len(nums) - 1
+        total: int
+        res: list[int]
         while i < j:
             total = snums[i] + snums[j]
             if total == target:
diff --git a/python3/1/c.py b/python3/1/c.py
index 2b7e751..f4b7628 100644
--- a/python3/1/c.py
+++ b/python3/1/c.py
@@ -5,8 +5,11 @@
 
 class Solution:
     def twoSum(self, nums: list[int], target: int) -> list[int]:
-        visited = {}
+        visited: dict[int, int] = {}
 
+        i: int
+        num: int
+        diff: int
         for i, num in enumerate(nums):
             diff = target - num
             if diff in visited:
diff --git a/python3/217/a.py b/python3/217/a.py
index a1b8c31..6afbd28 100644
--- a/python3/217/a.py
+++ b/python3/217/a.py
@@ -5,10 +5,12 @@
 
 class Solution:
     def containsDuplicate(self, nums: list[int]) -> bool:
-        n = len(nums)
+        n: int = len(nums)
         if n < 2:
             return False
 
+        i: int
+        j: int
         # enumerate does not allow the last item to be skipped without slicing,
         # which would require linear auxiliary space.
         for i in range(n - 1):
diff --git a/python3/217/b.py b/python3/217/b.py
index 8550fc8..b190749 100644
--- a/python3/217/b.py
+++ b/python3/217/b.py
@@ -10,6 +10,8 @@ def containsDuplicate(self, nums: list[int]) -> bool:
 
         nums.sort()
 
+        i: int
+        num: int
         for i, num in enumerate(nums):
             # nums[0] is needlessly compared to nums[-1] so as to avoid
             # checking if i > 0 at every iteration.
diff --git a/python3/217/c.py b/python3/217/c.py
index 0ed644f..d7dea5c 100644
--- a/python3/217/c.py
+++ b/python3/217/c.py
@@ -8,8 +8,9 @@ def containsDuplicate(self, nums: list[int]) -> bool:
         if len(nums) < 2:
             return False
 
-        visited = set()
+        visited: set[int] = set()
 
+        num: int
         for num in nums:
             if num in visited:
                 return True
diff --git a/python3/242/b.py b/python3/242/b.py
index 036ccc3..6fd02ba 100644
--- a/python3/242/b.py
+++ b/python3/242/b.py
@@ -8,8 +8,10 @@ def isAnagram(self, s: str, t: str) -> bool:
         if len(s) != len(t):
             return False
 
-        count = {}
+        count: dict[str, int] = {}
 
+        i: int
+        c: str
         for i, c in enumerate(s):
             count[c] = count.get(c, 0) + 1
             count[t[i]] = count.get(t[i], 0) - 1