diff --git a/leetcode/1.py b/leetcode/1.py
index b646c56..1eef024 100644
--- a/leetcode/1.py
+++ b/leetcode/1.py
@@ -4,6 +4,7 @@
 
 class Solution:
     def twoSum(self, nums: list[int], target: int) -> list[int]:
+        """
         answer = []
         for i in range(len(nums)):
             another = target - nums[i]
@@ -25,6 +26,15 @@ class Solution:
                 return answer
 
         return answer
+        """
+        num_map = {}
+        for i, num in enumerate(nums):
+            complement = target - num
+            # reduce compare times
+            if complement in num_map:
+                return [num_map[complement], i]
+            num_map[num] = i
+        return []
 
 
 test = [3, 2, 4]