30 Days of Code

Day	Challenge	Solutions		Day	Challenge	Solutions
0	Hello, World	Java Python		15	Linked Lists	Java Python
1	Data Types	Java Python		16	Exceptions - String to Integer	Java Python
2	Operators	Java Python		17	More Exceptions	Java Python
3	Intro to Conditional Statements	Java Python		18	Queues and Stacks	Java Python
4	Class vs. Instance	Java Python		19	Interfaces	Java Python
5	Loops	Java Python		20	Sorting	Java Python
6	Let's Review	Java Python		21	Generics	Java Python
7	Arrays	Java Python		22	Binary Search Trees	Java Python
8	Dictionaries and Maps	Java Python		23	BST Level-Order Traversal	Java Python
9	Recursion	Java Python		24	More Linked Lists	Java Python
10	Binary Numbers	Java Python		25	Running Time and Complexity	Java Python
11	2D Arrays	Java Python		26	Nested Logic	Java Python
12	Inheritance	Java Python		27	Testing	Java Python
13	Abstract Classes	Java Python		28	RegEx, Patterns, and Intro to Databases	Java Python
14	Scope	Java Python		29	Bitwise AND	Java Python

Notes on Style

Since readers of this tutorial are probably somewhat new to programming, my solutions to this particular set of challenges prioritize code readability over small gains in efficiency or robustness.

That is, the type of long, dense, or convoluted "one-liner" solutions that some programmers enjoy showing off are not presented here, and input is assumed to mostly follow the constraints stated in each challenge.

Encouraging Good Practices

The code stubs and solutions HackerRank provides for many of these challenges sometimes encourage bad coding habits. These include hardcoded values and some non-standard naming/indentation schemes. To help show beginners the light, my solutions adhere more strictly to general community standards of clean, maintainble code.

Specifically, my Java solutions mostly follow Google's Java Style Guide, and my Python solutions mostly follow PEP 8. (I say "mostly" because the locked code and tests written by HackerRank sometimes force the use of unconventional names, imports, etc.)