added an optimised two sum code in python

Python/algorithms/arrays/two_sum.py

@@ -0,0 +1,21 @@
+def two_sum(nums, target):
+    """
+    Finds the first pair of indices in `nums` whose values sum up to `target`.
+
+    Args:
+        nums (list of int): The input list of numbers.
+        target (int): The target sum.
+
+    Returns:
+        list: A list containing the two indices of the numbers that add up to target.
+              Returns an empty list if no such pair exists.
+    """
+    seen = {}  # Dictionary to store number -> index mapping
+
+    for i, num in enumerate(nums):
+        complement = target - num
+        if complement in seen:
+            return [seen[complement], i]
+        seen[num] = i
+
+    return []  # Return empty list if no pair found