diff --git a/.plan b/.plan
index eca8072..4ac2d46 100644
--- a/.plan
+++ b/.plan
@@ -1,6 +1,10 @@
-Sep 7, 2024
+Sep 8, 2024
+
+solve all hashmap questions in top-150
+* re-solve "219. Contains Duplicate II"
+* investigate better approach for 202 solution
 
-investigate better approach for 202 solution
+Sep 7, 2024
 
 * solve "202. Happy Number"
 * re-solve "1. Two Sum"
@@ -20,5 +24,4 @@ Sep 2, 2024
 Sep 1, 2024
 
 complete top interview 150
-
 * solve "205. Isomorphic Strings"
diff --git a/src/contains_duplicate_ii.py b/src/contains_duplicate_ii.py
index cea1e93..8b55691 100644
--- a/src/contains_duplicate_ii.py
+++ b/src/contains_duplicate_ii.py
@@ -3,7 +3,7 @@ def containsNearbyDuplicate(self, nums: list[int], k: int) -> bool:
         cache: dict[int, int] = {}
 
         for i, num in enumerate(nums):
-            if num in cache and abs(cache[num] - i) <= k:
+            if num in cache and i - cache[num] <= k:
                 return True
             cache[num] = i