Strings:
Sparse Arrays - Medium
Dynamic Array - Easy
Even Odd String - Easy

Matrix:
Transpose Matrix - Easy
2D Matrix - Easy

Linked List:
Linked List Basic - Easy

Hash table:
Dictionaries and Maps - Easy

Graphs:
Tree Preorder Traversal - Easy
Binary Search Trees - Easy
BST Level Order Traversal - Easy
Island Path - Hard

Bitwise:
Bitwise AND - Medium
Binary Numbers - Easy

Sorting:
Bubble Sort - Easy

Miscellaneous:
Abstract Classes - Easy
Inheritance - Easy
Scope - Easy
Arithmetic Operators - Easy
Generics - Easy
Exceptions - String to Integer - Easy
More Exceptions - Propagating exceptions - Easy
Queues and Stacks - Palindromes - Easy
Recursion Factorial - Easy
Interfaces - Easy

Coding tools:
Coding tools - Some code to be reused