Hacker Rank Challenges

Playing with HackerRank challenges (my profile) for fun, but also to stay sharp and brush up on Computer Science fundamentals that so frequently pop up in FAANG style tech interviews. Solutions are coded in Java 8 and pass all available tests to earn full points.

Each solution's Result.java class comes with a corresponding set of unit tests. Using JUnit 5 along with AssertJ library for its convenient and fluent assertions. Test method names follow naming standard as outlined here.

Problems

Total problems solved: 73

Algorithms

Category	Problem	Difficulty	Solution
Implementation (18):
	Angry Professor	Easy	Result - Unit Test
	Sherlock and The Beast	Easy	Result - Unit Test
	Utopian Tree	Easy	Result - Unit Test
	Find Digits	Easy	Result - Unit Test
	Sherlock and Squares	Easy	Result - Unit Test
	Service Lane	Easy	Result - Unit Test
	Bigger is Greater	Medium	Result - Unit Test
	Cut the Sticks	Easy	Result - Unit Test
	Chocolate Feast	Easy	Result - Unit Test
	Caesar Cipher	Easy	Result - Unit Test
	Grid Search	Medium	Result - Unit Test
	Cavity Map	Easy	Result - Unit Test
	Manasa and Stones	Easy	Result - Unit Test
	Library Fine	Easy	Result - Unit Test
	ACM ICPC Team	Easy	Result - Unit Test
	Extra Long Factorial	Medium	Result - Unit Test
	Taum and B'day Challenge	Easy	Result - Unit Test
	Time in Words	Medium	Result - Unit Test
	Matrix Layer Rotation	Hard	Result - Unit Test
Strings (11):
	Funny String	Easy	Result - Unit Test
	Pangrams	Easy	Result - Unit Test
	Alternating Characters	Easy	Result - Unit Test
	Two Strings	Easy	Result - Unit Test
	Sherlock and Anagrams	Medium	Result - Unit Test
	Game of Thrones	Easy	Result - Unit Test
	Gemstones	Easy	Result - Unit Test
	Making Anagrams	Easy	Result - Unit Test
	Anagram	Easy	Result - Unit Test
	Palindrome Index	Easy	Result - Unit Test
	Common Child	Medium	Result - Unit Test
	Sherlock and the Valid String	Medium	Result - Unit Test
Bit Manipulation (4):
	Lonely Integer	Easy	Result - Unit Test
	Maximizing XOR	Easy	Result - Unit Test
	Flipping Bits	Easy	Result - Unit Test
	Sansa and XOR	Medium	Result - Unit Test
Sorting (7):
	Insertion Sort Part 1	Easy	Result - Unit Test
	Insertion Sort Part 2	Easy	Result - Unit Test
	Insertion Sort Running Time	Easy	Result - Unit Test
	Quicksort Part 1	Easy	Result - Unit Test
	Quicksort Part 2	Medium	Result - Unit Test
	Counting Sort Part 1	Easy	Result - Unit Test
	Counting Sort Part 2	Easy	Result - Unit Test
Dynamic Programming (1):
	The Maximum Subarray	Medium	Result - Unit Test

Data Structures

Category	Problem	Difficulty	Solution
Arrays (1):
	Sparse Arrays	Medium	Result - Unit Test
Heap (1):
	Find the Running Median	Hard	Result - Unit Test

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Solutions (Old Format)

TODO: Convert each problem to new format and add unit tests.

Algorithms

Category	Name	Difficulty	Problem	Solution
Sorting (2):
	Counting Sort Part 3	Easy	Problem	Solution
	Counting Sort Part 4	Moderate	Problem	Solution
Search (6):
	Sherlock and Array	Easy	Problem	Solution
	Ice Cream Parlor	Easy	Problem	Solution
	Missing Numbers	Moderate	Problem	Solution
	Connected Cells	Moderate	Problem	Solution
	Count Luck	Easy	Problem	Solution
	Cut the Tree	Moderate	Problem	Solution
Graph Theory (7):
	Breadth Shortest Reach	Moderate	Problem	Solution
	Dijkstra Shortest Reach	Difficult	Problem	Solution
	Prim's Special Subtree	Moderate	Problem	Solution
	Kruskal's Really Special Subtree	Difficult	Problem	Solution
	Even Tree	Moderate	Problem	Solution
	Journey to the Moon	Moderate	Problem	Solution
	Snakes and Ladders	Easy	Problem	Solution
Greedy (9):
	Grid Challenge	Easy	Problem	Solution
	Jim and the Orders	Easy	Problem	Solution
	Mark and Toys	Easy	Problem	Solution
	Two Arrays	Easy	Problem	Solution
	Priyanka and Toys	Easy	Problem	Solution
	Largest Permutation	Easy	Problem	Solution
	Flowers	Moderate	Problem	Solution
	Cutting Boards	Moderate	Problem	Solution
	Max Min	Moderate	Problem	Solution
Dynamic Programming (4):
	Fibonacci Modified	Moderate	Problem	Solution
	Coin Change	Moderate	Problem	Solution
	Candies	Moderate	Problem	Solution
	Stock Maximize	Moderate	Problem	Solution