diff --git a/CS notes/pages/Leetcode Intersection-of-Two-Arrays-II.md b/CS notes/pages/Leetcode Intersection-of-Two-Arrays-II.md
index a5c3b07..f19fe67 100644
--- a/CS notes/pages/Leetcode Intersection-of-Two-Arrays-II.md	
+++ b/CS notes/pages/Leetcode Intersection-of-Two-Arrays-II.md	
@@ -1,6 +1,7 @@
 # Leetcode Intersection-of-Two-Arrays-II
 
 #### 2022-06-11
+##### First revision 2022-06-27
 
 ---
 ##### Data structures:
@@ -61,6 +62,9 @@ Given two integer arrays `nums1` and `nums2`, return _an array of their intersec
 
 For the original problem, I thought up an O(m + n) algo, that uses C++'s [[cpp_std_unordered_map]], and for the second one, I use double pointer method.
 
+> [!tip]
+> Because elements can be duplicated and we need to know how many, we should use unordered map to store the item's appereance times, (Maybe multiset can work too.)
+
 > [!tip] Use [[cpp_std_unordered_map]] for a O(1) hash table when not sorted #tip 
 
 > [!tip] Use [[cpp_std_sort]] to sort anything. #tip 
diff --git a/CS notes/pages/Leetcode Maximum-Difference-Between-Increasing-Elements.md b/CS notes/pages/Leetcode Maximum-Difference-Between-Increasing-Elements.md
index 0a6fcf4..bdefe14 100644
--- a/CS notes/pages/Leetcode Maximum-Difference-Between-Increasing-Elements.md	
+++ b/CS notes/pages/Leetcode Maximum-Difference-Between-Increasing-Elements.md	
@@ -9,7 +9,7 @@
 > ##### Additional tags:
 > #leetcode
 > ##### Revisions:
-> Initial encounter: 2022-06-27
+> N/A
 
 ##### Related topics:
 ```expander
diff --git a/_templates/OJ Problem Notes.md b/_templates/OJ Problem Notes.md
index f4d513c..0e0ee79 100644
--- a/_templates/OJ Problem Notes.md	
+++ b/_templates/OJ Problem Notes.md	
@@ -11,8 +11,7 @@
 > ##### Additional tags:
 > #<platforms-like-leetcode> #<list-to-be-added>
 > ##### Revisions:
-> Initial encounter: {{date}}
-> 1st revision: <use-template-command-to-insert-date>
+> N/A
 
 ##### Related topics:
 ```expander