Solutions to online programming challenges - https://www.hackerrank.com
What is HackerRank? HackerRank is a technology company[1] that focuses on competitive programming challenges for both consumers and businesses[2] and has an online community of over one million computer programmers.[3] HackerRank's programming challenges can be solved in a variety of programming languages (including Java, C++, PHP, Python, SQL) and span multiple computer science domains. https://en.wikipedia.org/wiki/HackerRank
Solutions are coded using Java 8 / C#
| Topic | Challenge | Difficulty | Solution |
|---|---|---|---|
| Data Structures | Arrays: Left Rotation | Easy | Coming Soon |
| Data Structures | Strings: Making Anagrams | Easy | Coming Soon |
| Data Structures | Hash Tables: Ransom Note | Easy | Coming Soon |
| Data Structures | Linked Lists: Detect a Cycle | Easy | Coming Soon |
| Data Structures | Stacks: Balanced Brackets | Medium | Coming Soon |
| Data Structures | Queues: A Tale of Two Stacks | Medium | Coming Soon |
| Data Structures | Trees: Is This a Binary Search Tree? | Medium | Coming Soon |
| Data Structures | Heaps: Find the Running Median | Hard | Coming Soon |
| Data Structures | Tries: Contacts | Hard | Coming Soon |
| Algorithms | Sorting: Bubble Sort | Medium | Coming Soon |
| Algorithms | Sorting: Comparator | Medium | Coming Soon |
| Algorithms | Merge Sort: Counting Inversions | Hard | Coming Soon |
| Algorithms | Binary Search: Ice Cream Parlor | Medium | Coming Soon |
| Algorithms | DFS: Connected Cell in a Grid | Hard | Coming Soon |
| Algorithms | BFS: Shortest Reach in a Graph | Hard | Coming Soon |
| Techniques / Concepts | Time Complexity: Primality | Medium | Coming Soon |
| Techniques / Concepts | Recrusion: Fibonacci Numbers | Easy | Coming Soon |
| Techniques / Concepts | Recursion: Davis' Staircase | Medium | Coming Soon |
| Techniques / Concepts | DP: Coin Change | Hard | Coming Soon |
| Techniques / Concepts | Bit Manipulation: Lonely Integer | Easy | Coming Soon |
| Topic | Challenge | Difficulty | Solution |
|---|---|---|---|
| LinkedList | M-th to Last Element | Hard | Solution.cs |
| Coming Soon | Fibonacci Lite | Hard | Coming Soon |
| Coming Soon | Fibonacci Returns | Hard | Coming Soon |
| Coming Soon | Find the uncoupled integer | Hard | Coming Soon |
| Coming Soon | Balanced Delimiters | Hard | Coming Soon |
| Coming Soon | FizzBuzz Classic | Hard | Coming Soon |
| Coming Soon | Factorial of n | Hard | Coming Soon |
| Coming Soon | The Coin Change Problem | Hard | Coming Soon |
| Subdomain | Challenge | Difficulty | Solution |
|---|---|---|---|
| Arrays | Arrays - DS | Easy | Coming Soon |
| Arrays | 2D Array - DS | Easy | Coming Soon |
| Arrays | Dynamic Array | Easy | Coming Soon |
| Arrays | Left Rotation | Easy | Coming Soon |
| Arrays | Sparse Arrays | Medium | Coming Soon |
| Arrays | Algorithmic Crush | Hard | Coming Soon |
| Linked List | Print the Elements of a Linked List | Easy | Coming Soon |
| Linked List | Insert a Node at the Tail of a Linked List | Easy | Coming Soon |
| Linked List | Insert a node at the head of a linked list | Easy | Coming Soon |
| Linked List | Insert a node at a specific position in a linked list | Easy | Coming Soon |
| Linked List | Delete a Node | Easy | Coming Soon |
| Linked List | Print in Reverse | Easy | Coming Soon |
| Linked List | Reverse a linked list | Easy | Coming Soon |
| Linked List | Compare two linked lists | Easy | Coming Soon |
| Linked List | Merge two sorted linked lists | Easy | Coming Soon |
| Linked List | Get Node Value | Easy | Coming Soon |
| Linked List | Delete duplicate-value nodes from a sorted linked list | Easy | Coming Soon |
| Linked List | Cycle Detection | Medium | Coming Soon |
| Linked List | Find Merge Point of Two Lists | Easy | Coming Soon |
| Linked List | Inserting a Node Into a Sorted Doubly Linked List | Easy | Coming Soon |
| Linked List | Reverse a doubly linked list | Easy | Coming Soon |
| Trees | Tree: Preorder Traversal | Easy | Solution.java |
| Trees | Tree: Postorder Traversal | Easy | Solution.java |
| Trees | Tree: Inorder Traversal | Easy | Coming Soon |
| Trees | Tree: Height of a Binary Tree | Easy | Coming Soon |
| Trees | Tree: Top View | Easy | Coming Soon |
| Trees | Tree: Level Order Traversal | Easy | Coming Soon |
| Trees | Binary Search Tree: Insertion | Easy | Solution.java |
| Trees | Tree: Huffman Decoding | Medium | [Solution.java] |
| Trees | Binary Search Tree: Lowest Common Ancestor | Easy | Coming Soon |
| Trees | Swap Nodes [Algo] | Medium | Coming Soon |
| Trees | Is This a Binary Search Tree? | Medium | Coming Soon |
| Trees | Square-Ten Tree | Hard | Coming Soon |
| Trees | Balanced Forest | Hard | Coming Soon |
| Balanced Trees | Self Balancing Tree | Medium | Coming Soon |
| Balanced Trees | Array and simple queries | Hard | Coming Soon |
| Balanced Trees | Median Updates | Hard | Coming Soon |
| Stacks | Maximum Element | Easy | |
| Stacks | Balanced Brackets | Medium | |
| Stacks | Largest Rectangle | Hard | Coming Soon |
| Stacks | Simple Text Editor | Medium | Coming Soon |
| Stacks | Equal Stacks | Easy | Coming Soon |
| Stacks | Poisonous Plants | Hard | Coming Soon |
| Stacks | AND xor OR | Hard | Coming Soon |
| Stacks | Waiter | Medium | Coming Soon |
| Queues | Queue using Two Stacks | Medium | |
| Queues | Castle on the Grid | Medium | Coming Soon |
| Queues | Down to Zero II | Medium | Coming Soon |
| Queues | Truck Tour | Hard | Coming Soon |
| Queues | Queries with Fixed Length | Hard | Coming Soon |
| Heap | QHEAP1 | Easy | Coming Soon |
| Heap | Jesse and Cookies | Easy | Coming Soon |
| Heap | Find the Running Median | Hard | Coming Soon |
| Heap | Minimum Average Waiting Time | Hard | Coming Soon |
| Disjoint Set | Merging Communities | Hard | Coming Soon |
| Disjoint Set | Components in a graph | Medium | Coming Soon |
| Disjoint Set | Kundu and Tree | Hard | Coming Soon |
| Disjoint Set | Super Maximum Cost Queries | Hard | Coming Soon |
| Multiple Choice | Data Structures MCQ 1 | Hard | Coming Soon |
| Multiple Choice | Data Structures MCQ 2 | Hard | Coming Soon |
| Multiple Choice | Data Structures MCQ 3 | Hard | Coming Soon |
| Trie | Contacts | Medium | Coming Soon |
| Trie | No Prefix Set | Hard | Coming Soon |
| Advanced | Kindergarten Adventures | Medium | Coming Soon |
| Advanced | Cube Summation | Hard | Coming Soon |
| Advanced | Mr. X and His Shots | Medium | Coming Soon |
| Advanced | Direct Connections | Hard | Coming Soon |
| Advanced | Subsequence Weighting | Advanced | Coming Soon |
| Advanced | Jim and the Skyscrapers | Medium | Coming Soon |
| Advanced | Counting On a Tree | Expert | Coming Soon |
| Advanced | Unique Colors | Advanced | Coming Soon |
| Advanced | Self-Driving Bus | Advanced | Coming Soon |
| Advanced | Fibonacci Numbers Tree | Expert | Coming Soon |
| Advanced | Functional Palindromes | Advanced | Coming Soon |
| Advanced | Lazy White Falcon | Hard | Coming Soon |
| Advanced | Ticket to Ride | Expert | Coming Soon |
| Advanced | Heavy Light White Falcon | Hard | Coming Soon |
| Advanced | Sum of the Maximums | Advanced | Coming Soon |
| Advanced | Heavy Light 2 White Falcon | Hard | Coming Soon |
| Advanced | Library Query | Advanced | Coming Soon |
| Advanced | Starfleet | Advanced | Coming Soon |
| Advanced | Almost Equal - Advanced | Expert | Coming Soon |
| Advanced | Almost sorted interval | Expert | Coming Soon |
| Advanced | Burger Happiness | Hard | Coming Soon |
| Advanced | Roy and alpha-beta trees | Hard | Coming Soon |
| Advanced | Coloring Tree | Hard | Coming Soon |
| Advanced | Recalling Early Days GP with Trees | Hard | Coming Soon |
| Advanced | Swaps and Sum | Advanced | Coming Soon |
| Advanced | Arithmetic Progressions | Advanced | Coming Soon |
| Advanced | Coolguy and Two Subsequences | Advanced | Coming Soon |
| Advanced | White Falcon And Tree | Hard | Coming Soon |
| Advanced | Subtrees And Paths | Advanced | Coming Soon |
| Advanced | Triplets | Advanced | Coming Soon |
| Advanced | Beautiful Segments | Expert | Coming Soon |
| Advanced | Divisibility | Expert | Coming Soon |
| Advanced | BST maintenance | Advanced | Coming Soon |
| Advanced | Find Maximum Index Product | Medium | Coming Soon |
| Advanced | Taxicab Driver's Problem | Advanced | Coming Soon |
| Advanced | Jaggu Playing with Balloons | Advanced | Coming Soon |
| Advanced | Dynamic Summation | Hard | Coming Soon |
| Advanced | Two Array Problem | Hard | Coming Soon |
| Advanced | Rooted Tree | Hard | Coming Soon |
| Advanced | The crazy helix | Advanced | Coming Soon |
| Advanced | Network administration | Hard | Coming Soon |
| Advanced | Easy Addition | Expert | Coming Soon |
| Advanced | Find the permutation | Expert | Coming Soon |
| Advanced | Company Retreat | Advanced | Coming Soon |