diff --git a/sum.py b/sum.py
new file mode 100644
index 0000000..91363a1
--- /dev/null
+++ b/sum.py
@@ -0,0 +1,9 @@
+class Solution:
+    def twoSum(self, nums, target):
+        seen = {}
+        for i, num in enumerate(nums):
+            diff = target - num
+            if diff in seen:
+                return [seen[diff], i]
+            seen[num] = i
+