diff --git a/dynamic_programming/longest_sub_array.py b/dynamic_programming/longest_sub_array.py
index b477acf61e66..0f4c691af117 100644
--- a/dynamic_programming/longest_sub_array.py
+++ b/dynamic_programming/longest_sub_array.py
@@ -10,24 +10,55 @@
 """
 
 
-class SubArray:
-    def __init__(self, arr):
-        # we need a list not a string, so do something to change the type
-        self.array = arr.split(",")
-
-    def solve_sub_array(self):
-        rear = [int(self.array[0])] * len(self.array)
-        sum_value = [int(self.array[0])] * len(self.array)
-        for i in range(1, len(self.array)):
-            sum_value[i] = max(
-                int(self.array[i]) + sum_value[i - 1], int(self.array[i])
-            )
-            rear[i] = max(sum_value[i], rear[i - 1])
-        return rear[len(self.array) - 1]
+def longest_sub_array(arr: list):
+    """
+    Find the longest continuous subarray with the maximum sum.
+
+    Args:
+    arr (list): A list of integers.
+
+    Returns:
+    A Integer which is the max subarray sum in the whole array.
+
+    Examples:
+    >>> longest_sub_array([1, 2, 3, 2, 5])
+    13
+
+    >>> longest_sub_array([5, -4, 3, -2, 1])
+    5
+
+    >>> longest_sub_array([1, 2, 3, -2, 5])
+    9
+
+    >>> longest_sub_array([10, 20, -30, 40, 50])
+    90
+
+    >>> longest_sub_array([])
+    0
+    """
+
+    max_so_far = arr[0]
+    max_ending_here = arr[0]
+    max_len = 1
+    curr_len = 1
+
+    for i in range(1, len(arr)):
+        if max_ending_here < 0:
+            max_ending_here = arr[i]
+            curr_len = 1
+        else:
+            max_ending_here += arr[i]
+            curr_len += 1
+        if max_ending_here > max_so_far:
+            max_so_far = max_ending_here
+            max_len = curr_len
+        elif max_ending_here == max_so_far:
+            max_len = max(max_len, curr_len)
+
+    return max_len
 
 
 if __name__ == "__main__":
-    whole_array = input("please input some numbers:")
-    array = SubArray(whole_array)
-    re = array.solve_sub_array()
-    print(("the results is:", re))
+    import doctest
+
+    doctest.testmod()
diff --git a/maths/sigmoid_linear_unit.py b/neural_network/activation_functions/sigmoid_linear_unit.py
similarity index 100%
rename from maths/sigmoid_linear_unit.py
rename to neural_network/activation_functions/sigmoid_linear_unit.py