912. Sort an Array.

    - Language: Python.
    - Time complexity: O(n log n).
    - Space complexity: O(2n + log n), O(log n) - for call stack.
    - Method: Recursive Merge Sort With Single Buffer.

Author: welder87

python_solutions/lc_912_sort_an_array/lc_912_sort_an_array.py

@@ -23,3 +23,40 @@ def _merge_two_arrays(self, ar1: list[int], ar2: list[int]) -> list[int]:
                 ans[i + j] = ar2[j]
                 j += 1
         return ans
+
+    def sortArrayV1(self, nums: list[int]) -> list[int]:
+        # Time complexity: O(n log n). Space complexity: O(2n).
+        # Method: Recursive Merge Sort With Single Buffer.
+        buffer = [0] * len(nums)
+        self._merge_sort_v1(nums, buffer, 0, len(nums) - 1)
+        return nums
+
+    def _merge_sort_v1(self, nums: list[int], buffer: list[int], left: int, right: int):
+        len = right - left + 1
+        if len < 2:
+            return nums
+        mid = (right + left) // 2
+        self._merge_sort_v1(nums, buffer, left, mid)
+        self._merge_sort_v1(nums, buffer, mid + 1, right)
+        self._merge_two_arrays_v1(nums, buffer, left, mid, mid + 1, right)
+
+    def _merge_two_arrays_v1(
+        self,
+        nums: list[int],
+        buffer: list[int],
+        left1: int,
+        right1: int,
+        left2: int,
+        right2: int,
+    ) -> None:
+        i, j, n = left1, left2, left1
+        while i <= right1 or j <= right2:
+            if j > right2 or i <= right1 and nums[i] < nums[j]:
+                buffer[n] = nums[i]
+                i += 1
+            else:
+                buffer[n] = nums[j]
+                j += 1
+            n += 1
+        for n in range(left1, right2 + 1):
+            nums[n] = buffer[n]

python_solutions/lc_912_sort_an_array/test_lc_912_sort_an_array.py

@@ -24,6 +24,11 @@ def test_success_v0(nums: list[int], ans: list[int], solution: Solution):
     assert solution.sortArray(nums) == ans
 
 
+@pytest.mark.parametrize(("nums", "ans"), test_cases)
+def test_success_v1(nums: list[int], ans: list[int], solution: Solution):
+    assert solution.sortArrayV1(nums) == ans
+
+
 @pytest.fixture
 def solution() -> Solution:
     return Solution()