readme

README.md

@@ -224,7 +224,7 @@ I have solved quite a number of problems from several topics. See the below tabl
 |13| [100. Same Tree](https://leetcode.com/problems/same-tree/)| [Python](leetcode.com/python/100_Same_Tree.py)| |
 |14| [11. Minimum Depth of Binary Tree](https://leetcode.com/problems/minimum-depth-of-binary-tree/)| [Python](leetcode.com/python/111_Minimum_Depth_of_Binary_Tree.py)| | Easy | --- |
 |15| [110. Balanced Binary Tree](https://leetcode.com/problems/balanced-binary-tree/)| [Python](leetcode.com/python/110_Balanced_Binary_Tree.py)| [Video 1](https://www.youtube.com/watch?v=LU4fGD-fgJQ), [Article 1](https://leetcode.com/problems/balanced-binary-tree/discuss/36042/Two-different-definitions-of-balanced-binary-tree-result-in-two-different-judgments), [Article 2](https://leetcode.com/problems/balanced-binary-tree/discuss/35708/VERY-SIMPLE-Python-solutions-(iterative-and-recursive)-both-beat-90) | Easy | --- |
-|16| [315. Count of Smaller Numbers After Self](https://leetcode.com/problems/count-of-smaller-numbers-after-self/)| [Python](leetcode.com/python/315_Count_of_Smaller_Numbers_After_Self.py)| [Article 1](https://leetcode.com/problems/count-of-smaller-numbers-after-self/discuss/76657/3-ways-(Segment-Tree-Binary-Indexed-Tree-Binary-Search-Tree)-clean-python-code), [Article 2](https://medium.com/@timtim305/leetcode-315-count-of-smaller-numbers-after-self-be529cdfe148), [Vid 1](https://www.youtube.com/watch?v=CWDQJGaN1gY), [Vid 2](https://www.youtube.com/watch?v=ZBHKZF5w4YU) | Hard (Very) | 📌 It's a very hard and advanced problem and need to check again. But before that, learn more on [Binary Indexed Tree](https://www.youtube.com/watch?v=CWDQJGaN1gY), [Segment Tree](https://www.youtube.com/watch?v=ZBHKZF5w4YU), Self-Balancing Trees like [AVL-Tree](https://www.educative.io/courses/data-structures-in-python-an-interview-refresher/JYlwQZmN7V9) and [Red-Black Tree](https://www.educative.io/courses/data-structures-in-python-an-interview-refresher/YQy7Zlz1mEO) also on Bit Manipulation |
+|16| [315. Count of Smaller Numbers After Self](https://leetcode.com/problems/count-of-smaller-numbers-after-self/)| [Python](leetcode.com/python/315_Count_of_Smaller_Numbers_After_Self.py)| [Article 1](https://leetcode.com/problems/count-of-smaller-numbers-after-self/discuss/76657/3-ways-(Segment-Tree-Binary-Indexed-Tree-Binary-Search-Tree)-clean-python-code), [Article 2](https://medium.com/@timtim305/leetcode-315-count-of-smaller-numbers-after-self-be529cdfe148), [Vid 1](https://www.youtube.com/watch?v=CWDQJGaN1gY), [Vid 2](https://www.youtube.com/watch?v=ZBHKZF5w4YU) | Hard (Very) |📌Very hard. First learn [BIT](https://www.youtube.com/watch?v=CWDQJGaN1gY), [ST](https://www.youtube.com/watch?v=ZBHKZF5w4YU), [AVL-Tree](https://www.educative.io/courses/data-structures-in-python-an-interview-refresher/JYlwQZmN7V9) and [Red-Black Tree](https://www.educative.io/courses/data-structures-in-python-an-interview-refresher/YQy7Zlz1mEO) then try again|
 
 
 ### [Tries](https://leetcode.com/explore/learn/card/trie/)
@@ -240,7 +240,7 @@ I have solved quite a number of problems from several topics. See the below tabl
 
 | #  | Title | Solution | Tutorial | Level | Remarks |
 | --- | --- | --- | --- | --- | --- |
-|01| [200. Number of Islands](https://leetcode.com/problems/number-of-islands/)| [Python](leetcode.com/python/200_Number_of_Islands.py)|
+|01| [200. Number of Islands](https://leetcode.com/problems/number-of-islands/)| [Python](leetcode.com/python/200_Number_of_Islands.py)| --- | Medium | DFS, Union Find |
 
 
 ### [Recursion, Iteration](https://leetcode.com/explore/learn/card/recursion-i/)
@@ -553,7 +553,6 @@ Learn the following modules by heart. Just knowing all of the following items wi
 01. [Graph Theory Playlist](https://tinyurl.com/rfgy88b)
 02. [Union Find \[Disjoint Set\] Playlist](https://tinyurl.com/srz7uua)
 03. [Disjoint Sets Data Structure - Weighted Union and Collapsing Find](https://www.youtube.com/watch?v=wU6udHRIkcc)
-0. []()
 
 <b>Bit Manipulation</b>
 01. [Bit Manipulation - youtube](https://www.youtube.com/watch?v=7jkIUgLC29I)