diff --git a/leetcode/stuff.py b/leetcode/stuff.py
index 3fc6a18..71761f9 100644
--- a/leetcode/stuff.py
+++ b/leetcode/stuff.py
@@ -535,3 +535,22 @@ def copy_random_list(
             ordered_copy[i].random = ordered_copy[hash_idx[hash(entry.random)]]
 
     return ordered_copy[0]
+
+
+def sum_max_sub_array(nums: list[int]) -> int:
+    window_size: int = 1
+    begin: int = 0
+    end: int = window_size
+    max_sum: int = sum(nums)
+
+    while end - begin <= len(nums):
+        while end < len(nums):
+            max_sum = max(max_sum, sum(nums[begin:end]))
+            begin += 1
+            end += 1
+
+        window_size += 1
+        begin = 0
+        end = window_size
+
+    return max_sum
diff --git a/leetcode/test_stuff.py b/leetcode/test_stuff.py
index 27cb0e3..8a2555d 100644
--- a/leetcode/test_stuff.py
+++ b/leetcode/test_stuff.py
@@ -444,3 +444,24 @@ def test_trie_busy():
     assert trie.startsWith("rent") is True
     assert trie.startsWith("beer") is True
     assert trie.startsWith("jam") is True
+
+
+@pytest.mark.parametrize(
+    ("nums", "expected"),
+    [
+        (
+            [-2, 1, -3, 4, -1, 2, 1, -5, 4],
+            6,
+        ),
+        (
+            [1],
+            1,
+        ),
+        (
+            [5, 4, -1, 7, 8],
+            23,
+        ),
+    ],
+)
+def test_maximum_subarray(nums: list[int], expected: int):
+    assert stuff.sum_max_sub_array(nums) == expected