refactor: optimize pair sum lookup with set

Author: AhmadHmedann

Sprint-1/Python/has_pair_with_sum/has_pair_with_sum.py

@@ -3,16 +3,27 @@
 Number = TypeVar("Number", int, float)
 
 
+# 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:
+#     Space Complexity:
+#     Optimal time complexity:
+#     """
+#     for i in range(len(numbers)):
+#         for j in range(i + 1, len(numbers)):
+#             if numbers[i] + numbers[j] == target_sum:
+#                 return True
+#     return False
+
 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.
+    seen  = set()
+    for num in numbers:
+        needed = target_sum - num
+        if needed in seen:
+            return True
+
+        seen.add(num)
 
-    Time Complexity:
-    Space Complexity:
-    Optimal time complexity:
-    """
-    for i in range(len(numbers)):
-        for j in range(i + 1, len(numbers)):
-            if numbers[i] + numbers[j] == target_sum:
-                return True
     return False