Create running_sum_1d_array

Python/algorithms/arrays/running_sum_1d_array

@@ -0,0 +1,46 @@
+from typing import List
+
+def running_sum(nums: List[int]) -> List[int]:
+    """
+    Compute the running sum of a 1D array.
+
+    Given an integer array nums, return the running sum such that:
+        running_sum[i] = nums[0] + nums[1] + ... + nums[i]
+
+    Time Complexity: O(n)
+    Space Complexity: O(n)
+
+    Args:
+        nums (List[int]): List of integers.
+
+    Returns:
+        List[int]: Running sum of the input list.
+
+    Example:
+        >>> running_sum([1, 2, 3, 4])
+        [1, 3, 6, 10]
+    """
+    n = len(nums)
+    if n == 0:
+        return []
+
+    ans = [0] * n
+    ans[0] = nums[0]
+
+    for i in range(1, n):
+        ans[i] = ans[i - 1] + nums[i]
+
+    return ans
+
+
+if __name__ == "__main__":
+    # quick test cases
+    examples = [
+        ([1, 2, 3, 4], [1, 3, 6, 10]),
+        ([1, 1, 1, 1, 1], [1, 2, 3, 4, 5]),
+        ([3, 1, 2, 10, 1], [3, 4, 6, 16, 17]),
+        ([], []),
+    ]
+
+    for arr, expected in examples:
+        print(f"{arr} -> {running_sum(arr)} (expected {expected})")