Basics:

1. All about bits (Stanford Unv , basecs)
2. Number System (basecs)
3. Modular Arithmetic (Khan Academy)
4. Data Types (Wiki)
5. What is an asymptote? (wiki)
6. Asymptotic Analysis (gfg , youtube , youtube)
7. Abstract Data Type (gfg)
8. Recursion (youtube , gfg ,medium)

Data Structures:

1. Arrays (gfg , wiki , problems)
2. Matrix (wiki)
3. LinkedList ( gfg , basecs)
4. Stacks and queues (basecs)
5. Hashtable (wiki , youtube , basecs)
6. Tree (freecodecamp , stackoverflow , youtube)
   • Binary tree (gfg)
   • AVL Tree (gfg)
   • Segment Tree (gfg)
   • Heaps (youtube , gfg)
7. Suffix Array ( youtube , codechef , gfg)
8. Suffix Tree ( gfg , stackoverflow)
9. Graphs (topcoder , basecs , youtube)
10. Disjoint Set data structure (gfg , wiki)
11. Tries (topcoder , youtube)
12. Palindromic Tree (gfg , blog)
13. Complete DS guide on geeksforgeeks.

Algorithms:

1. What is an algorithm? (wiki)
   • Tool to visualize algorithms: https://visualgo.net/en
2. Searching
   • Linear search (gfg)
   • Binary search ( topcoder , gfg)
   • Jump search ( gfg )
3. Sorting
   • Radix Sort (MIT Opencourseware)
   • Tim Sort (GKCS Part 1, GKCS Part 2)