diff --git a/labs/lab_1/lab_1a.py b/labs/lab_1/lab_1a.py
index 9d15ec83..128931f7 100644
--- a/labs/lab_1/lab_1a.py
+++ b/labs/lab_1/lab_1a.py
@@ -1,4 +1,4 @@
-"""
+##"This is to simulate a change made on a robot: robot_speed = 8# m/s""
 lab_1a.py
 
 The first lab in the BWSI CSS course. To complete this lab, fill out the variable on line 10
@@ -8,9 +8,10 @@
 def main():
     print("Hello World!")
 
-    name = "" # TODO: Insert your name between the double quotes
+    name = "Oluj" # TODO: Insert your name between the double quotes
 
     print(f"{name}, Welcome to the CSS course!")
+    print("This is my personal introduction from the beginning of the course!")
 
 if __name__ == "__main__":
     main()
diff --git a/labs/lab_1/lab_1b.py b/labs/lab_1/lab_1b.py
index e58dd957..bcaefad9 100644
--- a/labs/lab_1/lab_1b.py
+++ b/labs/lab_1/lab_1b.py
@@ -37,6 +37,12 @@ def simple_calculator(operation: str, num1: float, num2: float) -> float:
     else:
         raise ValueError("Invalid operation. Please choose from 'add', 'subtract', 'multiply', or 'divide'.")
 
+def request_sanitized_number(prompt: str) -> float:
+    while True:
+        try:
+            return float(input(prompt))
+        except ValueError:
+            print("Invalid input. Please enter a valid number.")
 def main():
     
     print(f"===== Simple Calculator =====")
diff --git a/labs/lab_1/lab_1c.py b/labs/lab_1/lab_1c.py
index 40cf98db..f2853bf7 100644
--- a/labs/lab_1/lab_1c.py
+++ b/labs/lab_1/lab_1c.py
@@ -1,14 +1,3 @@
-"""
-lab_1c.py
-
-Given a list of numbers, return the maximum sum of any contiguous subarray of the list.
-
-Do not assume anything. Account for all edge cases.
-
-Derived from LeetCode problem: https://leetcode.com/problems/maximum-subarray/ (leetcode medium)
-"""
-
-# TODO: Find and resolve the bug in the following implementation. Create unit tests to verify your fix.
 def max_subarray_sum(nums: list[int]) -> int:
     """
     Function that takes in a list of integers and returns the maximum sum of any contiguous subarray.
@@ -18,22 +7,18 @@ def max_subarray_sum(nums: list[int]) -> int:
 
     Returns:
         int: The maximum sum of any contiguous subarray.
+
+    Raises:
+        ValueError: If nums is empty.
     """
+    if not nums:
+        raise ValueError("nums must not be empty")
 
     max_current = max_global = nums[0]
-    
-    for num in nums:
+
+    for num in nums[1:]:
         max_current = max(num, max_current + num)
-        if max_current < max_global:
+        if max_current > max_global:
             max_global = max_current
-            
-    return max_global
-
-# Example usage:
-def main():
-    nums = [-2,1,-3,4,-1,2,1,-5,4]
-    result = max_subarray_sum(nums)
-    print(f"Maximum subarray sum: {result}")
 
-if __name__ == "__main__":
-    main()
\ No newline at end of file
+    return max_global
\ No newline at end of file
diff --git a/tests/test_1d.py b/tests/test_1d.py
new file mode 100644
index 00000000..3cd2ba1c
--- /dev/null
+++ b/tests/test_1d.py
@@ -0,0 +1,31 @@
+import unittest
+
+def two_sum(nums: list[int], target: int) -> list[int]:
+    num_to_index = {}
+    for index, num in enumerate(nums):
+        complement = target - num
+        if complement in num_to_index:
+            return [num_to_index[complement], index]
+        num_to_index[num] = index
+    return []
+
+
+class TestTwoSum(unittest.TestCase):
+    def test_basic_case(self):
+        self.assertEqual(two_sum([2, 7, 11, 15], 9), [0, 1])
+
+    def test_other_case(self):
+        self.assertEqual(two_sum([3, 2, 4], 6), [1, 2])
+
+    def test_duplicate_values(self):
+        self.assertEqual(two_sum([3, 3], 6), [0, 1])
+
+    def test_negative_numbers(self):
+        self.assertEqual(two_sum([-1, -2, -3, -4, -5], -8), [2, 4])
+
+    def test_no_solution_fallback(self):
+        self.assertEqual(two_sum([1, 2, 3], 100), [])
+
+
+if __name__ == "__main__":
+    unittest.main()
\ No newline at end of file
diff --git a/tests/tests_1c.py b/tests/tests_1c.py
new file mode 100644
index 00000000..94e9f59b
--- /dev/null
+++ b/tests/tests_1c.py
@@ -0,0 +1,45 @@
+import unittest
+
+def max_subarray_sum(nums: list[int]) -> int:
+    if not nums:
+        raise ValueError("nums must not be empty")
+
+    max_current = max_global = nums[0]
+
+    for num in nums[1:]:
+        max_current = max(num, max_current + num)
+        if max_current > max_global:
+            max_global = max_current
+
+    return max_global
+
+
+class TestMaxSubarraySum(unittest.TestCase):
+    def test_example_case(self):
+        self.assertEqual(max_subarray_sum([-2, 1, -3, 4, -1, 2, 1, -5, 4]), 6)
+
+    def test_single_positive(self):
+        self.assertEqual(max_subarray_sum([5]), 5)
+
+    def test_single_negative(self):
+        self.assertEqual(max_subarray_sum([-5]), -5)
+
+    def test_all_negative(self):
+        self.assertEqual(max_subarray_sum([-8, -3, -6, -2, -5, -4]), -2)
+
+    def test_all_positive(self):
+        self.assertEqual(max_subarray_sum([1, 2, 3, 4]), 10)
+
+    def test_mixed_values(self):
+        self.assertEqual(max_subarray_sum([5, -2, 3, 4]), 10)
+
+    def test_contains_zeroes(self):
+        self.assertEqual(max_subarray_sum([0, 0, 0]), 0)
+
+    def test_empty_list_raises(self):
+        with self.assertRaises(ValueError):
+            max_subarray_sum([])
+
+
+if __name__ == "__main__":
+    unittest.main()
\ No newline at end of file