Introduction ✔

1. Intro
   1. 28 March, 2026: 00.28.15 ❌
      • Failed at edge cases
   • Add a new Node class outside LinkedList

     class Node{
     public:
         int val;
         Node* next;
         Node(int val){
             this->val = val;
             this->next = NULL;
         }
     };

   • Define required static variable inside LinkedList class but outside consider.

     int size = 0;
     Node* head; 
     Node* tail;
     MyLinkedList() {
         head = tail = NULL;
         size = 0;
     }

2. Insertion
   1. 28 March, 2026: 00.21.13 ✔
3. Delete
4. Length
5. Search

• https://leetcode.com/problems/remove-linked-list-elements
  1. 26 March, 2026: 00.07.09 ✔
     • Just make a new head, connected with corresponded element
• https://leetcode.com/problems/merge-two-sorted-lists
  1. 27 March, 2026: 00.03.11 ✔
• https://leetcode.com/problems/finding-pairs-with-a-certain-sum/
  1. 28 March, 2026: 00.18.47 ❌
     • Failed at optimization
     • Solve count within $O(n1)$, having hashmap inside count make the complexity $O((n2)^2)$ as each time count invoked, so keep it in constructor.