use set to improve

Author: aydaeslami

Sprint-1/Python/has_pair_with_sum/has_pair_with_sum.py

@@ -8,11 +8,25 @@ def has_pair_with_sum(numbers: List[Number], target_sum: Number) -> bool:
     Find if there is a pair of numbers that sum to a target value.
 
     Time Complexity:
+        ANSWER: O(n)
+        Because the list is looped through once.
+
     Space Complexity:
+        ANSWER: O(n)
+        Because a set is used to store seen numbers.
+
     Optimal time complexity:
+        ANSWER: O(n)
+        Each number is processed once using a set for faster lookup.
+
+
     """
-    for i in range(len(numbers)):
-        for j in range(i + 1, len(numbers)):
-            if numbers[i] + numbers[j] == target_sum:
-                return True
+    seen = set()
+
+    for number in numbers:
+        complement = target_sum - number
+        if complement in seen:
+            return True
+        seen.add(number)
+
     return False