HackerRank
HackerRank solutions in Java/JS/Python/C++/C#
MIT License
Stars
1.3K
Algorithms 
- Warmup
- Implementation
- Strings
- Sorting
- Search
- Graph Theory
- Greedy
- Dynamic Programming
- Constructive Algorithms
- Bit Manipulation
- Recursion
- Game Theory
- NP Complete
DataStructures 
- Arrays
- Linked Lists
- Trees
- Balanced Trees
- Stacks
- Queues
- Heap
- Disjoint Set
- Multiple Choice
- Trie
- Advanced
Mathematics 
- Fundamentals
- Number Theory
- Combinatorics
- Algebra
- Geometry
- Probability
- Linear Algebra Foundations
Java 
- Introduction
- Strings
- BigNumber
- Data Structures
- Object Oriented Programming
- Exception Handling
- Advanced
Warmup
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Solve Me First | Java C# | O(1) | O(1) | Easy | 1 | ||
| Simple Array Sum | Java C# | O(n) | O(1) | Easy | 10 | ||
| Compare the Triplets | Java C# | O(1) | O(1) | Easy | 10 | ||
| A Very Big Sum | Java C# | O(n) | O(1) | Easy | 10 | ||
| Diagonal Difference | JavaC# | O(n) | O(1) | Easy | 10 | ||
| Plus Minus | JavaC# | O(n) | O(1) | Easy | 10 | ||
| Staircase | JavaC# | O(n) | O(n) | Easy | 10 | ||
| Mini-Max Sum | JavaC# | O(1) | O(1) | Easy | 10 | ||
| Time Conversion | JavaC# | O(1) | O(1) | Easy | 15 | ||
| Birthday Cake Candles | JavaC# | O(n) | O(1) | Easy | 10 |
Implementation
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Grading Students | Java JS C# | O(n) | O(1) | Easy | 10 | ||
| Apple and Orange | Java JS C# | O(n+m) | O(1) | Easy | 10 | ||
| Kangaroo | Java C# | O(1) | O(1) | Easy | 10 | ||
| Between Two Sets | Java C# | O(x(n+m)) | O(1) | Easy | 10 | x=(max(m) - min(n))/min(n) | |
| Divisible Sum Pairs | JavaC# | O(n^2) | O(1) | Easy | 10 | ||
| Birthday Chocolate | Java C# | O(n) | O(1) | Easy | 10 | ||
| Breaking the Records | Java C# | O(n) | O(1) | Easy | 10 | ||
| Migratory Birds | Java JSC# | O(n) | O(1) | Easy | 10 | ||
| Day of the Programmer | JavaC# | O(1) | O(1) | Easy | 15 | ||
| Bon Appetit | JavaC# | O(n) | O(1) | Easy | 10 | ||
| Sock Merchant | Java C# | O(n) | O(n) | Easy | 10 | ||
| Drawing Book | Java C# | O(1) | O(1) | Easy | 10 | ||
| Counting Valleys | Java JS C# | O(n) | O(1) | Easy | 15 | ||
| Cats and a Mouse | Java C# | O(1) | O(1) | Easy | 15 | ||
| Electronics Shop | Java JS C# | O(n log (n)) | O(1) | Easy | 15 | n = m+n | |
| Picking Numbers | Java C# | O(n) | O(n) | Easy | 20 | ||
| Climbing the Leaderboard | Java JS C# | O(n+m) | (n) | Easy | 20 | ||
| The Hurdle Race | Java C# | O(n) | O(1) | Easy | 15 | ||
| Designer PDF Viewer | Java JS C# | O(n) | O(n) | Easy | 20 | ||
| Forming a Magic Square | Java | O(1) | O(1) | Easy | 20 | ||
| Utopian Tree | Java JS C# | O(n) | O(1) | Easy | 20 | ||
| Angry Professor | Java JS C# | O(n) | O(1) | Easy | 20 | ||
| Beautiful Days at the Movies | Java JS C# | O(n) | O(1) | Easy | 15 | ||
| Viral Advertising | Java JS C# | O(n) | O(1) | Easy | 15 | ||
| Save the Prisoner! | Java C# | O(1) | O(1) | Easy | 15 | ||
| Circular Array Rotation | Java C# | O(n) | O(1) | Easy | 20 | ||
| Sequence Equation | Java C# | O(n) | O(n) | Easy | 20 | ||
| Jumping on the Clouds: Revisited | Java C# | O(n) | O(n) | Easy | 15 | ||
| Find Digits | Java C# | O(n) | O(1) | Easy | 25 | ||
| Extra Long Factorials | Java C# | O(n) | O(1) | Medium | 20 | ||
| Append and Delete | Java | O(n) | O(1) | Easy | 20 | ||
| Sherlock and Squares | Java | O(n) | O(1) | Easy | 20 | ||
| Library Fine | Java C# | O(1) | O(1) | Easy | 15 | ||
| Cut the sticks | Java C# | O(n log(n)) | O(n) | Easy | 25 | ||
| Non-Divisible Subset | Java | O(n) | O(n) | Medium | 20 | ||
| Repeated String | Java C# | O(n) | O(n) | Easy | 20 | ||
| Jumping on the Clouds | JavaC# | O(n) | O(n) | Easy | 20 | ||
| Equalize the Array | JavaC# | O(n) | O(n) | Easy | 20 | ||
| Queen's Attack II | Java | O(k) | O(1) | Medium | 30 | ||
| ACM ICPC Team | Java | O(n^3) | O(n) | Easy | 25 | ||
| Taum and B'day | JavaC# | O(1) | O(1) | Easy | 25 | ||
| Organizing Containers of Balls | Java | O(n^2) | O(n^2) | Medium | 30 | ||
| Encryption | JavaC# | O(n) | O(1) | Medium | 30 | ||
| Bigger is Greater | Java | O(n) | O(n) | Medium | 35 | ||
| Modified Kaprekar Numbers | JavaC# | O(n) | O(1) | Easy | 30 | ||
| Minimum Distances | JavaC# | O(n) | O(n) | Easy | 20 | ||
| Beautiful Triplets | JavaC# | O(n) | O(n) | Easy | 20 | ||
| Strings: Making Anagrams | Java | O(|a|+|b|) | O(1) | Easy | 30 | ||
| The Time in Words | JavaC# | O(1) | O(1) | Medium | 25 | ||
| Chocolate Feast | JavaC# | O(log(n)) | O(1) | Easy | 25 | Base of logarithmic time complexity is m | |
| Service Lane | JavaC# | O(n) | O(n) | Easy | 20 | ||
| Lisa's Workbook | JavaC# | O(n) | O(1) | Easy | 25 | ||
| Flatland Space Stations | JavaC# | O(n) | O(n) | Easy | 25 | ||
| Fair Rations | JavaC# | O(n) | O(1) | Easy | 25 | ||
| Cavity Map | JavaC# | O(n^2) | O(n^2) | Easy | 30 | ||
| Manasa and Stones | JavaC# | O(n) | O(1) | Easy | 30 | ||
| The Grid Search | Java | O(n) | O(n) | Medium | 30 | n = len(word) | |
| Happy Ladybugs | Java | O(n) | O(n) | Easy | 30 | ||
| Strange Counter | Java | O(n) | O(1) | Easy | 30 | n = t | |
| Absolute Permuation | Java | O(n) | O(n) | Medium | 40 | ||
| The Bomberman Game | Java | O(n*m) | O(n*m) | Medium | 40 | ||
| Ema's Supercomputer | Java | Medium | 40 | ||||
| Larry's Array | Java | Medium | 40 | ||||
| Almost Sorted | Java | Medium | 50 | ||||
| Matrix Layer Rotation | Python3 | O(n*m) | O(n*m) | Hard | 80 | ||
| Consecutive 1s in Binary Numbers | Java | O(n) | O(1) | Easy | 30 | ||
| Nested Logic | Java | O(1) | O(1) | Easy | 40 | ||
| Bitwise AND | Java | O(1) | O(1) | Easy | 20 |
Strings
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Super Reduced String | JavaC# | O(n) | O(n) | Easy | 10 | ||
| camelCase | JavaC# | O(n) | O(1) | Easy | 15 | ||
| Strong Password | C# | O(n) | O(1) | Easy | 15 | ||
| Two Characters | JavaC# | O(n) | O(n) | Easy | 15 | ||
| Caesar Cipher | JavaC# | O(n) | O(n) | Easy | 15 | ||
| Caesar Cipher: Encryption | Java | O(n) | O(n) | Easy | 40 | ||
| Mars Exploration | JavaC# | O(n) | O(1) | Easy | 15 | ||
| HackerRank in a String! | Java JSC# | O(n) | O(1) | Easy | 20 | ||
| Pangrams | JavaC# | O(n) | O(1) | Easy | 20 | ||
| Weighted Uniform Strings | JavaC# | O(n) | O(n) | Easy | 20 | ||
| Separate the Numbers | JavaC# | O(n) | O(n) | Easy | 20 | ||
| Funny String | JavaC# | O(n) | O(n) | Easy | 25 | ||
| Gemstones | JavaC# | O(n) | O(1) | Easy | 20 | ||
| Alternating Characters | JavaC# | O(n) | O(1) | Easy | 20 | ||
| Beautiful Binary String | Java | O(n) | O(1) | Easy | 20 | ||
| The Love-Letter Mystery | Java | O(n) | O(1) | Easy | 20 | ||
| Determining DNA Health | Java | Hard | 50 | ||||
| Palindrome Index | Java | O(n) | O(1) | Easy | 25 | ||
| Anagram | Java | O(n) | O(1) | Easy | 25 | ||
| Making Anagrams | Java | O(n) | O(n) | Easy | 30 | ||
| Game of Thrones - I | JavaC# | O(n) | O(1) | Easy | 30 | ||
| Two Strings | JavaC# | O(|a| + |b|) | O(1) | Easy | 25 | a and b are lengths of the input strings | |
| String Construction | Java | O(n) | O(n) | Easy | 25 | ||
| Sherlock and Valid String | Java | O(n) | O(n) | Hard | 100 | ||
| Richie Rich | Java Python3 | O(n) | O(n) | Medium | 30 | ||
| Sherlock and Anagrams | Java | Medium | 50 | ||||
| Common Child | Java | Hard | 60 | ||||
| Bear and Steady Gene | Java | Medium | 50 | ||||
| Morgan and a String | Java | O((|a|+|b|)^2) | O(|a| + |b|) | Expert | 100 | ||
| Count Strings | Java | Hard | 80 | ||||
| String Function Calculation | Java | Advanced | 80 | ||||
| Build a Palindrome | Java | Advanced | 80 | ||||
| Build a String | Java | Hard | 80 | ||||
| Gridland Provinces | Java | Hard | 80 | ||||
| Ashton and String | Java | Advanced | 100 | ||||
| String Similarity | Java | Expert | 100 | ||||
| Super Functional Strings | Java | Advanced | 80 | ||||
| Circular Palindromes | Java | Advanced | 120 | ||||
| Similar Strings | Java | Advanced | 85 | ||||
| Save Humanity | Java | Expert | 100 | ||||
| Find Strings | Java | Expert | 100 | ||||
| Palindromic Border | Java | Expert | 100 | ||||
| Two Two | Java | Advanced | 150 | ||||
| Two Strings Game | Java | Expert | 100 | ||||
| Letter Islands | Java | Expert | 100 | ||||
| Pseudo-Isomorphic Substrings | Java | Expert | 100 | ||||
| How Many Substrings? | Java | Expert | 100 |
Sorting
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Intro to Tutorial Challenges | JavaC# | O(n) | O(1) | Easy | 30 | ||
| Insertion Sort - Part 1 | JavaC# | O(n) | O(1) | Easy | 30 | ||
| Insertion Sort - Part 2 | JavaC# | O(n^2) | O(1) | Easy | 30 | ||
| Correctness and the Loop Invariant | JavaC# | O(n^2) | O(1) | Easy | 30 | ||
| Running Time of Algorithms | JavaC# | O(n^2) | O(1) | Easy | 30 | ||
| Quicksort 1 - Partition | JavaC# | O(n) | O(n) | Easy | 10 | ||
| Quicksort 2 - Sorting | JavaC# | O(n^2) | O(n) | Easy | 30 | ||
| Quicksort In-Place | Java | O(n^2) | O(log(n)) | Medium | 35 | ||
| Running Time of Quicksort | Java | O(n log(n)) | O(log(n)) | Easy | 35 | ||
| Counting Sort 1 | JavaC# | O(n+k) | O(k) | Easy | 30 | value of k in this problem is 100 | |
| Counting Sort 2 | JavaC# | O(n+k) | O(n+k) | Easy | 30 | Value of k is 100 in this problem. | |
| Counting Sort 3 | Java | O(n+k) | O(k) | Easy | 30 | ||
| The Full Counting Sort | JavaC# | O(n+k) | O(n+k) | Medium | 40 | ||
| Closest Numbers | JavaC# | O(n log(n)) | O(n) | Easy | 35 | ||
| Find the Median | JavaC# | O(n log(n)) | O(n) | Easy | 35 | ||
| Insertion Sort Advanced Analysis | Java | Advanced | 50 | ||||
| Fraudulent Activity Notifications | Java | O(n^2) | O(n) | Medium | 40 | ||
| Lily's Homework | Java | O(n log(n)) | O(n) | Medium | 40 | ||
| Big Sorting | JavaC# | O(n log(n)) | O(n) | Easy | 20 |
Search
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Hackerland Radio Transmitters | JSC# | O(n log(n)) | O(n) | Medium | 25 | ||
| Ice Cream Parlor | JavaC# | O(n) | O(n) | Easy | 30 | ||
| Binary Search: Ice Cream Parlor | Java | O(n) | O(n) | Easy | 35 | ||
| Gridland Metro | JavaC# | O(k) | O(k) | Medium | 25 | k = number of tracks | |
| Missing Numbers | Java C++C# | O(n) | O(n) | Easy | 45 | ||
| Minimum Loss | Java | O(n log(n)) | O(n) | Medium | 35 | ||
| KnightL on a Chessboard | Java | Medium | 35 | ||||
| Pairs | Java C++C# | O(n log(n)) | O(n) | Medium | 50 | ||
| Sherlock and Array | Java C++C# | O(n) | O(n) | Easy | 40 | ||
| Maximum Subarray Sum | Java | Hard | 65 | ||||
| Connected Cells in a grid | Java | Medium | 50 | ||||
| Short Palindrome | Java | Medium | 40 | ||||
| Maximizing Mission Points | Java | Hard | 70 | ||||
| Count Luck | Java | Medium | 50 | ||||
| Cut the Tree | Java | Medium | 50 | ||||
| Making Candies | Java | Hard | 45 | ||||
| Gena Playing Hanoi | Java | Medium | 50 | ||||
| Beautiful Quadruples | Java | Medium | 50 | ||||
| Bike Racers | Java | Hard | 65 | ||||
| Task Scheduling | Java | Advanced | 70 | ||||
| Similar Pair | Java | Advanced | 70 | ||||
| Absolute Element Sums | Java | Hard | 70 | ||||
| Sorted Subsegments | Java | Hard | 80 | ||||
| Distant Pairs | Java | Expert | 80 | ||||
| King Richard's Knights | Java | Hard | 80 |
Graph Theory
Greedy
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Minimum Absolute Difference in an Array | Java JSC# | O(n log(n)) | O(n) | Easy | 15 | ||
| Chief Hopper | Java | O(n) | O(n) | Hard | 65 | ||
| Mark and Toys | Java JS | O(n log(n)) | O(n) | Easy | 35 | ||
| Marc's Cakewalk | JavaC# | O(n + k) | O(k) | Easy | 15 | ||
| Grid Challenge | Java | O(n*(n log (n))) | O(n^2) | Easy | 20 | ||
| Luck Balance | Java | O(n log(n)) | O(1) | Easy | 20 | ||
| Maximum Perimeter Triangle | Java | O(n log (n)) | O(n) | Easy | 20 | ||
| Permuting Two Arrays | Java JS | O(n log (n)) | O(n) | Easy | 40 | ||
| Jim and the Orders | Java | O(n log (n)) | O(n) | Easy | 40 | ||
| Equal Stacks | Java | O(n) | O(n) | Easy | 25 | ||
| Sherlock and The Beast | Java | O(n) | O(n) | Easy | 30 | ||
| Priyanka and Toys | Java JS | O(n log(n)) | O(n) | Easy | 30 | ||
| Largest Permutation | JS | O(n) | O(n) | Easy | 30 | ||
| Beautiful Pairs | Java | Easy | 30 | ||||
| Yet Another Minimax Problem | Java | Medium | 20 | ||||
| Flipping the Matrix | Java | O(n^2) | O(n^2) | Medium | 30 | ||
| Roads and Libraries | Java | Medium | 30 | ||||
| Greedy Florist | JS | O(n log (n)) | O(n) | Medium | 35 | ||
| Mark and Toys | Java | O(n log(n)) | O(n) | Easy | 35 | ||
| Max Min | Java | O(n log(n)) | O(1) | Medium | 35 | ||
| Permuting Two Arrays | Java | Easy | 40 | ||||
| Jim and the Orders | Java | Easy | 40 | ||||
| Goodland Electricity | Java | Medium | 40 | ||||
| Fun Game | Java | Medium | 40 | ||||
| Reverse Shuffle Merge | Java | Advanced | 50 | ||||
| Cutting Boards | Java | Hard | 60 | ||||
| Algorithmic Crush | Java | Hard | 60 | ||||
| Prim's (MST): Special Subtree | Java | Medium | 60 | ||||
| Accessory Collection | Java | Hard | 60 | ||||
| Chief Hopper | Java | O(n) | O(n) | Hard | 65 | ||
| Sherlock and MiniMax | Java | Hard | 70 | ||||
| Team Formation | Java | Advanced | 70 |
Dynamic Programming
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Equal | Java | Medium | 30 | ||||
| Cut Tree | Java | Medium | 40 | ||||
| Mr K marsh | Java | Medium | 40 | ||||
| Sam and sub-strings | Java | Medium | 40 | ||||
| Summing Pieces | Java | Medium | 40 | ||||
| Short Palindrome | Java | Medium | 40 | ||||
| Abbreviation | Java | Medium | 40 | ||||
| Fair Cut | Java | Medium | 40 | ||||
| Fibonacci Modified | Java | Medium | 45 | ||||
| Lego Blocks | Java | Medium | 50 | ||||
| Candies | Java | Medium | 50 | ||||
| Stock Maximize | Java | Medium | 50 | ||||
| Angry Childtren 2 | Java | Hard | 50 | ||||
| The Maximum Subarray | Java | Medium | 50 | ||||
| Sherlock and Cost | Java | Medium | 50 | ||||
| Xor and Sum | Java | Medium | 50 | ||||
| Counting Special Sub-Cubes | Java | Medium | 50 | ||||
| Two Robots | Java | Medium | 50 | ||||
| Kingdom Division | Java | Medium | 50 | ||||
| Prime XOR | Java | Medium | 50 | ||||
| HackerRank City | Java | Medium | 50 | ||||
| Nikita and the Game | Java | Medium | 50 | ||||
| Prime Digit Sums | Java | Medium | 50 | ||||
| Mandragora Forest | Java | Medium | 50 | ||||
| LCS Returns | Java | Medium | 50 | ||||
| Grid Walking | Java | Medium | 55 | ||||
| Bricks Game | Java | Medium | 55 | ||||
| The Longest Common Subsequence | Java | Medium | 55 | ||||
| Substring Diff | Java | Medium | 60 | ||||
| Brick Tiling | Java | Hard | 60 | ||||
| Alien Languages | Java | Hard | 60 | ||||
| The Longest Increasing Subsequence | Java | Advanced | 60 | ||||
| The Coin Change Problem | Python3 | O(N*M) | O(N) | Hard | 60 | ||
| Knapsack | Java | Medium | 60 | ||||
| Sherlock's Array Merging Algorithm | Java | Hard | 60 | ||||
| New Year Game | Java | Medium | 60 | ||||
| Shashank and the Palindromic Strings | Java | Advanced | 60 | ||||
| Decibinary Numbers | Java | Hard | 60 | ||||
| Choosing White Balls | Java | Hard | 60 | ||||
| DP: Coin Change | Java | Hard | 60 | ||||
| Clues on a Binary Path | Java | Hard | 60 | ||||
| GCD Matrix | Java | Hard | 60 | ||||
| Coin on the Table | Java | Medium | 65 | ||||
| Interval Selection | Java | Medium | 65 | ||||
| Red John is Back | Java | Medium | 65 | ||||
| Play with words | Java | Medium | 65 | ||||
| Queens on Board | Java | Hard | 70 | ||||
| String Reduction | Java | Hard | 70 | ||||
| Far Vertices | Java | Hard | 70 | ||||
| The Indian Job | Java | Medium | 70 | ||||
| Hexagonal Grid | Java | Hard | 70 | ||||
| Longest Palindromic Subsequence | Java | Hard | 70 | ||||
| Turn Off the Lights | Java | Hard | 70 | ||||
| Tara's Beautiful Permutations | Java | Hard | 70 | ||||
| Two Subarrays | Java | Expert | 70 | ||||
| Mining | Java | Advanced | 75 | ||||
| The Longest Common Subsequence (LCS) | Java | Hard | 75 | ||||
| Points in a Plane | Java | Advanced | 80 | ||||
| Fairy Chess | Java | Advanced | 80 | ||||
| Billboards | Java | Advanced | 80 | ||||
| Requirement | Java | Advanced | 80 | ||||
| A Super Hero | Java | Hard | 80 | ||||
| Covering the stains | Java | Hard | 80 | ||||
| Superman Celebrates Diwali | Java | Hard | 80 | ||||
| Wet Shark and Two Subsequences | Java | Medium | 80 | ||||
| Zurikela's Graph | Java | Hard | 80 | ||||
| New Year Present | Java | Hard | 80 | ||||
| Suffix Rotation | Java | Expert | 80 | ||||
| Black and White Tree | Java | Hard | 80 | ||||
| Beautiful Strings | Java | Hard | 80 | ||||
| Longest Mod Path | Java | Hard | 80 | ||||
| Super Functional Strings | Java | Advanced | 80 | ||||
| Kitty's Calculations on a Tree | Java | Advanced | 80 | ||||
| Liars | Java | Advanced | 85 | ||||
| Dorsey Thief | Java | Advanced | 85 | ||||
| Swap Permutation | Java | Medium | 85 | ||||
| Candles Counting | Java | Medium | 85 | ||||
| Square Subsequences | Java | Hard | 90 | ||||
| Hyper Strings | Java | Advanced | 90 | ||||
| Unique Divide And Conquer | Java | Advanced | 90 | ||||
| Super Kth LIS | Java | Advanced | 90 | ||||
| Counting Road Networks | Java | Expert | 90 | ||||
| Lucky Numbers | Java | Expert | 100 | ||||
| Count Scorecards | Java | Expert | 100 | ||||
| Unfair Game | Java | Advanced | 100 | ||||
| Oil Well | Java | Hard | 100 | ||||
| Modify The Sequence | Java | Advanced | 100 | ||||
| Divisible Numbers | Java | Expert | 100 | ||||
| Ones and Twos | Java | Hard | 100 | ||||
| Extremum Permutations | Java | Medium | 100 | ||||
| Tree Pruning | Java | Advanced | 100 | ||||
| P-sequences | Java | Hard | 100 | ||||
| Best spot | Java | Advanced | 100 | ||||
| Find the Seed | Java | Advanced | 100 | ||||
| The Blacklist | Java | Advanced | 100 | ||||
| Police Operation | Java | Hard | 100 | ||||
| Road Maintenance | Java | Hard | 100 | ||||
| King and Four Sons | Java | Expert | 100 | ||||
| Counting the Ways | Java | Expert | 100 | ||||
| Hard Disk Drives | Java | Expert | 100 | ||||
| Travel around the world | Java | Medium | 120 | ||||
| Robot | Java | Advanced | 120 | ||||
| Vim War | Java | Advanced | 120 | ||||
| Dortmund Dilemma | Java | Advanced | 150 | ||||
| Separate the chocolate | Java | Expert | 250 |
Constructive Algorithms
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Lena Sort | Java | Medium | 30 | ||||
| Flipping the Matrix | Java | O(n^2) | O(n^2) | Medium | 30 | ||
| Gaming Array | Java | Medium | 35 | ||||
| New Year Chaos | Java | Medium | 40 | ||||
| Bonetrousle | Java | Medium | 50 | ||||
| Yet Another KMP Problem | Java | Hard | 60 | ||||
| Beautiful 3 Set | Java | Hard | 60 | ||||
| Inverse RMQ | Java | Hard | 60 | ||||
| Two Subarrays | Java | Expert | 70 | ||||
| Lovely Triplets | Java | Advanced | 80 | ||||
| Array Construction | Java | Advanced | 80 |
Bit Manipulation
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Lonely Integer | Java | O(n) | O(1) | Easy | 20 | ||
| Maximizing XOR | Java | Easy | 30 | ||||
| Counter game | Java | Medium | 30 | ||||
| Xor-sequence | Java | Medium | 40 | ||||
| Sum vs XOR | Java | O(n log(n)) | O(1) | Easy | 20 | ||
| The Great XOR | Java | Medium | 25 | ||||
| Flipping bits | Java | Easy | 40 | ||||
| Yet Another Minimax Problem | Java | Medium | 30 | ||||
| Sansa and XOR | Java | Medium | 30 | ||||
| AND Product | Java | Medium | 40 | ||||
| Xoring Ninja | Java | Hard | 55 | ||||
| Cipher | Java | Medium | 50 | ||||
| XOR Matrix | Java | Hard | 50 | ||||
| What's Next? | Java | Medium | 50 | ||||
| String Transmission | Java | Hard | 60 | ||||
| A or B | Java | Medium | 50 | ||||
| Manipulative Numbers | Java | Hard | 55 | ||||
| Stone game | Java | Hard | 70 | ||||
| 2's complement | Java | Advanced | 70 | ||||
| Changing Bits | Java | Advanced | 70 | ||||
| XOR key | Java | Advanced | 80 | ||||
| Maximizing the Function | Java | Hard | 70 | ||||
| XOR Subsequences | Java | Advanced | 80 | ||||
| Iterate It | Java | Expert | 90 | ||||
| Hamming Distance | Java | Expert | 150 | ||||
| Mixing proteins | Java | Hard | 80 |
Recursion
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| The Power Sum | Java | Easy | 20 | ||||
| Crossword Puzzle | Java | Medium | 30 | ||||
| Recursive Digit Sum | Java | Medium | 30 | ||||
| Simplified Chess Engine | Java | Medium | 40 | ||||
| Password Cracker | Java | Medium | 40 | ||||
| Artithmetic Expressions | Java | Hard | 40 | ||||
| K Factorization | Java | Hard | 50 | ||||
| Bowling Pins | Java | Advanced | 60 | ||||
| Simplified Chess Engine II | Java | Hard | 60 | ||||
| Repetitive K-Sums | Java | Advanced | 150 |
Game Theory
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Game of Stones | JS | O(n) | O(1) | Easy | 15 | ||
| Tower Breakers | Java | Easy | 15 | ||||
| A Chessboard Game | Java | Easy | 15 | ||||
| Introduction to Nim Game | Java | Easy | 15 | ||||
| Misère Nim | Java | Easy | 20 | ||||
| Nimble Game | Java | Easy | 20 | ||||
| Alice and Bob's Silly Game | Java | Medium | 30 | ||||
| Poker Nim | Java | Easy | 20 | ||||
| Tower Breakers, Revisited! | Java | Medium | 25 | ||||
| Tower Breakers, Again! | Java | Medium | 30 | ||||
| Zero-Move Nim | Java | Medium | 50 | ||||
| Chessboard Game, Again! | Java | Medium | 30 | ||||
| Digits Square Board | Java | Medium | 35 | ||||
| Fun Game | Java | Medium | 40 | ||||
| Stone Division | Java | Hard | 50 | ||||
| Chocolate in Box | Java | Medium | 70 | ||||
| Kitty and Katty | Java | Medium | 80 | ||||
| Powers Game | Java | Medium | 50 | ||||
| Deforestation | Java | Medium | 50 | ||||
| Bob and Ben | Java | Medium | 50 | ||||
| Tower Breakers - The Final Battle | Java | Medium | 50 | ||||
| Simple Game | Java | Hard | 60 | ||||
| Permutation game | Java | Medium | 70 | ||||
| Move the Coins | Java | Hard | 60 | ||||
| Play on benders | Java | Medium | 70 | ||||
| New Year Game | Java | Medium | 60 | ||||
| Stone Piles | Java | Hard | 80 | ||||
| Chocolate Game | Java | Hard | 90 | ||||
| Manasa and Prime game | Java | Hard | 90 | ||||
| Vertical Rooks | Java | Medium | 90 | ||||
| A stones game | Java | Medium | 90 | ||||
| Tastes Like Winning | Java | Expert | 100 |
NP Complete
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Walking the Approximate Longest Path | Java | Hard | 70 | ||||
| Sam's Puzzle (Approximate) | Java | Advanced | 85 | ||||
| Spies, Revised | Java | Expert | 100 | ||||
| TBS Problem | Java | Expert | 100 |
Object Oriented Programming
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Class vs. Instance | Java | N/A | N/A | Easy | 30 | ||
| Inheritance | Java | O(n) | O(1) | Easy | 30 | ||
| Abstract Classes | Java | N/A | N/A | Easy | 30 | ||
| Complex Numbers | Java | O(1) | O(1) | Easy | 30 |
Arrays
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Arrays - DS | C++ | O(n) | O(n) | Easy | 10 | ||
| 2D Array - DS | C++ | O(1) | O(1) | Easy | 15 | ||
| Sparse Arrays | C# | O(n + q) | O(n + q) | Medium | 25 | n = number of input strings, q = number of queries | |
| Dynamic Array | C# | O(q) | O(n) | Easy | 15 | q = Number of queries |
Linked Lists
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Print the Elements of a Linked List | C++ | O(n) | O(1) | Easy | 5 | ||
| Reverse a Linked List | Java | O(n) | O(1) | Easy | 5 | ||
| Compare Two Linked Lists | C++ | O(n) | O(1) | Easy | 5 | ||
| Delete a node | C++ | O(n) | O(1) | Easy | 5 |
Trees
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Tree: Preorder Traversal | C++ | O(n) | O(n) | Easy | 10 | ||
| Swap Nodes [Algo] | C# | O(n) | O(n) | Medium | 40 |
Balanced Trees
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Self Balancing Tree | C++ | O(log(n)) | O(n) | Medium | 50 |
Stacks
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Maximum Element | C++ | Push-O(1), Delete - O(n), Print - O(1) | Push - O(1), Delete - O(1), Print - O(1) | Easy | 20 | ||
| Balanced Brackets | Java | O(n) | O(n) | Medium | 25 |
Queues
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Queue using Two Stacks | C# | Enqueue - O(1), Dequeue - O(n), Print - O(n) | Enqueue - O(1), Dequeue - O(1), Print - O(1) | Medium | 30 |
Heap
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| QHEAP1 | C# | Insert - O(log(n)), Delete - O(n), Print - O(1) | Insert - O(1), Delete - O(1), Print - O(1) | Easy | 25 |
Disjoint Set
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Spaceholder | C# | O(1) | O(1) | Easy | 1 |
Multiple Choice
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Data Structures MCQ 1 | Language Independent | NA | NA | Hard | 5 | ||
| Data Structures MCQ 2 | Language Independent | NA | NA | Hard | 5 | ||
| Data Structures MCQ 3 | Language Independent | NA | NA | Hard | 5 |
Trie
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Contacts | C# | Add - O(L), Find - O(L) | Add - O(L), Find - O(1) | Medium | 40 | L = Length of a contact name |
Advanced
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Spaceholder | C# | O(1) | O(1) | Easy | 1 |
Fundamentals
| # | Title | Solution | Time | Space | Difficulty | Points | Note |
|---|---|---|---|---|---|---|---|
| Leonardo's Prime Factors | C# | O(1) | O(1) | Easy | 10 |