https://www.hackerrank.com/domains/tutorials/30-days-of-code
Day 1: Data Types
Day 2: Operators
Day 3: Intro to Conditional Statements
Day 4: Class vs. Instance
Day 5: Loops
Day 6: Let's Review
Day 7: Arrays
Day 8: Dictionaries and Maps
Day 9: Recursion
Day 10: Binary Numbers
Day 11: 2D-Arrays
Day 12: Inheritance
Day 13: Abstract Classes
Day 14: Scope
Day 15: Linked List
Day 16: Exceptions - String to Integer
Day 17: More Exceptions
Day 18: Queues and Stacks
Day 19: Interfaces
Day 20: Sorting
Day 21: Generics
Day 22: Binary Search Trees
Day 23: BST Level-Order Traversal
Day 24: More Linked Lists
Day 25: Running Time and Complexity
Day 26: Nested Logic
Day 27: Testing
Day 28: RegEx, Patterns, and Intro to Databases
Day 29: Bitwise AND
Pointer
Say "Hello, World!" With C++
2D Array - DS
Array Left Rotation
Arrays - DS
Print the Elements of a Linked List
A Very Big Sum
Angry Professor
Diagonal Difference
Find Digits
Pangrams
Plus Minus
Simple Array Sum
Staircase