Merge pull request #86 from MIT-Emerging-Talent/23-sort-colors

23 sort colors

solutions/sort_colors.py

@@ -4,37 +4,22 @@
 A module for sorting a list of numbers based on their colors.
 
 Module contents:
-    - sort_colors: sorts a list of integers representing colors (0, 1, 2) in ascending order.
+    - sort_colors: Sorts a list of integers representing colors (0, 1, 2) in ascending order.
 
 Dependencies:
     - typing: Used for type annotations (List).
 
-Notes:
-    - Does not use built-in sorting functions or libraries such as `sorted()` or `sort()`.
-    - Implements an in-place counting sort approach.
-    - Time complexity: O(n)
-    - Space complexity: O(1) (in-place).
-
 Created on 26 12 2024
 @author: Mohamed-Elnageeb
 """
 
-from typing import List  # Importing List for type annotations
+from typing import List
 
 
 def sort_colors(nums: List[int]) -> None:
     """
     Sorts a given list of integers representing colors (0, 1, 2) in-place.
 
-    This function implements sorting logic manually using a counting sort approach and does not use
-    any built-in sorting functions or libraries, such as `sorted()` or `sort()`.
-
-    Time Complexity:
-        O(n): Iterates through the list once to count occurrences and again to modify it in-place.
-
-    Space Complexity:
-        O(1): Uses a fixed-size counter list of size 3. No additional space is used.
-
     Parameters:
         nums: List[int]
             A list of integers where each integer is 0, 1, or 2. Modified in-place.
@@ -43,7 +28,8 @@ def sort_colors(nums: List[int]) -> None:
         None
 
     Raises:
-        AssertionError: if the input is not a list or contains invalid elements (numbers out of the range 0 to 2).
+        TypeError: If the input is not a list or if elements in the list are not integers.
+        AssertionError: If elements in the list are outside the range 0 to 2.
 
     Examples:
     >>> nums = [0, 2, 1]
@@ -61,18 +47,22 @@ def sort_colors(nums: List[int]) -> None:
     >>> nums
     [0, 1, 1, 2, 2]
     """
-    # Validate input
-    assert isinstance(nums, list), "Input must be a list."
-    assert all(0 <= number <= 2 for number in nums), "All elements must be 0, 1, or 2."
+    # Validate input type
+    if not isinstance(nums, list):
+        raise TypeError("Input must be a list.")
+    if not all(isinstance(number, int) for number in nums):
+        raise TypeError("All elements in the list must be integers.")
 
-    # Create a counter list to store the count of each number
-    counter_list = [0] * 3
+    # Validate input range
+    if not all(0 <= number <= 2 for number in nums):
+        raise AssertionError("All elements must be integers in the range 0, 1, or 2.")
 
-    # Count occurrences of each number
+    # Count occurrences of 0, 1, and 2
+    counter_list = [0] * 3
     for number in nums:
         counter_list[number] += 1
 
-    # Rebuild the nums list in-place
+    # Rebuild the list based on counts
     index = 0
     for number in range(3):
         for _ in range(counter_list[number]):

solutions/tests/test_sort_colors.py

@@ -21,9 +21,11 @@
   - test_randomly_generated_list: Tests with a randomly generated list.
 
 - Exception test cases:
-  - test_not_a_list: Ensures an AssertionError is raised for non-list inputs.
-  - test_invalid_elements: Ensures an AssertionError is raised for invalid
-    elements (e.g., elements not in the range [0, 2]).
+  - test_not_a_list: Ensures a TypeError is raised for non-list inputs.
+  - test_invalid_elements_type: Ensures a TypeError is raised for invalid
+    element types (e.g., non-integer elements).
+  - test_invalid_elements_range: Ensures an AssertionError is raised for invalid
+    elements (e.g., integers not in the range [0, 2]).
 
 Created on 26 10 2024
 
@@ -77,13 +79,19 @@ def test_large_list(self):
         self.assertEqual(nums, expected)
 
     def test_not_a_list(self):
-        """It should raise an assertion error if the input is not a list"""
-        with self.assertRaises(AssertionError):
+        """It should raise a TypeError if the input is not a list"""
+        with self.assertRaises(TypeError):
             sort_colors("not a list")
 
-    def test_invalid_elements(self):
-        """It should raise an assertion error for invalid elements"""
-        nums = [0, 1, 3]  # Invalid element 3
+    def test_invalid_elements_type(self):
+        """It should raise a TypeError for invalid element types"""
+        nums = [0, 1, "2"]  # Invalid element "2" (string)
+        with self.assertRaises(TypeError):
+            sort_colors(nums)
+
+    def test_invalid_elements_range(self):
+        """It should raise an AssertionError for elements out of range"""
+        nums = [0, 1, 3]  # Invalid element 3 (out of range)
         with self.assertRaises(AssertionError):
             sort_colors(nums)