This repository consists of solutions to HackerRank practice, tutorials, and interview preparation problems with Algorithms, Data Structures, Python, mySQL, C#, C++, C and JavaScript.
| Subdomain | Challenge | Problem | Difficulty | Solution |
|---|---|---|---|---|
| Introduction | Say "Hello, World!" With C++ | Problem | Easy | Solution |
| Introduction | Input And Output | Problem | Easy | Solution |
| Introduction | Basic Data Types | Problem | Easy | Solution |
| Introduction | Conditional Statements | Problem | Easy | Solution |
| Introduction | For Loop | Problem | Easy | Solution |
| Introduction | Functions | Problem | Easy | Solution |
| Introduction | Pointer | Problem | Easy | Solution |
| Introduction | Arrays Introduction | Problem | Easy | Solution |
| Introduction | Variable Sized Array | Problem | Easy | Solution |
| Strings | Attribute Parser | Problem | Medium | Solution |
| Strings | StringStream | Problem | Easy | Solution |
| Strings | Strings | Problem | Easy | Solution |
| Classes | Structs | Problem | Easy | Solution |
| Classes | Class | Problem | Easy | Solution |
| Classes | Classes and Objects | Problem | Easy | Solution |
| Classes | Box It! | Problem | Easy | Solution |
| Classes | Inherited Code | Problem | Medium | Solution |
| Classes | Exceptional Server | Problem | Medium | Solution |
| Classes | Virtual Functions | Problem | Medium | Solution |
| Classes | Abstract Classes - Polymorphism | Problem | Hard | Solution |
| STL | Vector-Sort | Problem | Easy | Solution |
| STL | Vector-Erase | Problem | Easy | Solution |
| STL | Lower Bound-STL | Problem | Easy | Solution |
| STL | Sets-STL | Problem | Easy | Solution |
| STL | Maps-STL | Problem | Easy | Solution |
| STL | Print Pretty | Problem | Easy | Solution |
| STL | Deque-STL | Problem | Medium | Solution |
| Inheritance | Inheritance Introduction | Problem | Easy | Solution |
| Inheritance | Rectangle Area | Problem | Easy | Solution |
| Inheritance | Multi Level Inheritance | Problem | Easy | Solution |
| Inheritance | Accessing Inherited Functions | Problem | Medium | Solution |
| Inheritance | Magic Spells | Problem | Hard | Solution |
| Debugging | Hotel Prices | Problem | Medium | Solution |
| Debugging | Cpp exception handling | Problem | Medium | Solution |
| Debugging | Overloading Ostream Operator | Problem | Medium | Solution |
| Debugging | Messages Order | Problem | Medium | Solution |
| Other Concepts | C++ Class Templates | Problem | Easy | Solution |
| Other Concepts | Preprocessor Solution | Problem | Easy | Solution |
| Other Concepts | Operator Overloading | Problem | Medium | Solution |
| Other Concepts | Overload Operators | Problem | Easy | Solution |
| Other Concepts | Attending Workshops | Problem | Medium | Solution |
| Other Concepts | C++ Class Template Specialization | Problem | Medium | Solution |
| Other Concepts | C++ Variadics | Problem | Hard | Solution |
| Other Concepts | Bit Array | Problem | Hard | Solution |
| Subdomain | Challenge | Problem | Difficulty | Solution |
|---|---|---|---|---|
| Introduction | Say 'Hello, World!' With Python | Problem | Easy | Solution |
| Introduction | Python If-Else | Problem | Easy | Solution |
| Introduction | Arithmetic Operators | Problem | Easy | Solution |
| Introduction | Python Division | Problem | Easy | Solution |
| Introduction | Loops | Problem | Easy | Solution |
| Introduction | Write a function | Problem | Medium | Solution |
| Introduction | Print Function | Problem | Easy | Solution |
| Basic Data Types | List Comprehensions | Problem | Easy | Solution |
| Basic Data Types | Find the Runner-Up Score! | Problem | Easy | Solution |
| Basic Data Types | Nested Lists | Problem | Easy | Solution |
| Basic Data Types | Finding the percentage | Problem | Easy | Solution |
| Basic Data Types | Lists | Problem | Easy | Solution |
| Basic Data Types | Tuples | Problem | Easy | Solution |
| Strings | sWAP cASE | Problem | Easy | Solution |
| Strings | String Split and Join | Problem | Easy | Solution |
| Strings | What's Your Name? | Problem | Easy | Solution |
| Strings | Mutations | Problem | Easy | Solution |
| Strings | Find a string | Problem | Easy | Solution |
| Strings | String Validators | Problem | Easy | Solution |
| Strings | Text Alignment | Problem | Easy | Solution |
| Strings | Text Wrap | Problem | Easy | Solution |
| Strings | Designer Door Mat | Problem | Easy | Solution |
| Strings | String Formatting | Problem | Easy | Solution |
| Strings | Alphabet Rangoli | Problem | Easy | Solution |
| Strings | Capitalize! | Problem | Easy | Solution |
| Strings | The Minion Game | Problem | Medium | Solution |
| Strings | Merge the Tools! | Problem | Medium | Solution |
| Sets | Introduction to Sets | Problem | Easy | Solution |
| Sets | No Idea! | Problem | Medium | Solution |
| Sets | Symmetric Difference | Problem | Easy | Solution |
| Sets | Set add() | Problem | Easy | Solution |
| Sets | Set discard() remove() pop() | Problem | Easy | Solution |
| Sets | Set union() Operation | Problem | Easy | Solution |
| Sets | Set intersection() Operation | Problem | Easy | Solution |
| Sets | Set difference() Operation | Problem | Easy | Solution |
| Sets | Set symmetric_difference() Operation | Problem | Easy | Solution |
| Sets | Set Mutations | Problem | Easy | Solution |
| Sets | The Captain's Room | Problem | Easy | Solution |
| Sets | Check Subset | Problem | Easy | Solution |
| Sets | Check Strict Superset | Problem | Easy | Solution |
| Math | Polar Coordinates | Problem | Easy | Solution |
| Math | Find Angle MBC | Problem | Medium | Solution |
| Math | Triangle Quest 2 | Problem | Medium | Solution |
| Math | Mod Divmod | Problem | Easy | Solution |
| Math | Power - Mod Power | Problem | Easy | Solution |
| Math | Integers Come In All Sizes | Problem | Easy | Solution |
| Math | Triangle Quest | Problem | Medium | Solution |
| Itertools | itertools.product() | Problem | Easy | Solution |
| Itertools | itertools.permutations() | Problem | Easy | Solution |
| Itertools | itertools.combinations() | Problem | Easy | Solution |
| Itertools | itertools.combinations_with_replacement() | Problem | Easy | Solution |
| Itertools | Compress the String! | Problem | Medium | Solution |
| Itertools | Iterables and Iterators | Problem | Medium | Solution |
| Itertools | Maximize It! | Problem | Hard | Solution |
| Collections | collections.Counter() | Problem | Easy | Solution |
| Collections | defaultdict Tutorial | Problem | Easy | Solution |
| Collections | collections.namedtuple() | Problem | Easy | Solution |
| Collections | collections.OrderedDict() | Problem | Easy | Solution |
| Collections | collections.deque() | Problem | Easy | Solution |
| Collections | Company Logo | Problem | Medium | Solution |
| Collections | Word Order | Problem | Medium | Solution |
| Collections | Piling Up! | Problem | Medium | Solution |
| Date and Time | Calendar Module | Problem | Easy | Solution |
| Date and Time | Time Delta | Problem | Medium | Solution |
| Errors and Exceptions | Exceptions | Problem | Easy | Solution |
| Errors and Exceptions | Incorrect Regex | Problem | Easy | Solution |
| Classes | Classes - Dealing with Complex Numbers | Problem | Medium | Solution |
| Classes | Class 2 - Find the Torsional Angle | Problem | Easy | Solution |
| Built-ins | Zipped! | Problem | Easy | Solution |
| Built-ins | Input() | Problem | Easy | Solution |
| Built-ins | Python Evalution | Problem | Easy | Solution |
| Built-ins | Athlete Sort | Problem | Medium | Solution |
| Built-ins | Any or All | Problem | Easy | Solution |
| Built-ins | ginortS | Problem | Medium | Solution |
| Python Functional | Map and Lambda Function | Problem | Easy | Solution |
| Python Functional | Validating Email Addresses With a Filter | Problem | Medium | Solution |
| Python Functional | Reduce Function | Problem | Medium | Solution |
| Regex and Parsing | Detect Floating Point Number | Problem | Easy | Solution |
| Regex and Parsing | Re.split() | Problem | Easy | Solution |
| Regex and Parsing | Group(), Groups(), & Groupdict() | Problem | Easy | Solution |
| Regex and Parsing | Re,findall() & Re.finditer() | Problem | Easy | Solution |
| Regex and Parsing | Re.start() & Re.end() | Problem | Easy | Solution |
| Regex and Parsing | Regex Substitution | Problem | Medium | Solution |
| Regex and Parsing | Validating Roman Numerals | Problem | Easy | Solution |
| Regex and Parsing | Validating phone numbers | Problem | Easy | Solution |
| Regex and Parsing | Validating and Parsing Email Addresses | Problem | Easy | Solution |
| Regex and Parsing | Hex Color Code | Problem | Easy | Solution |
| Regex and Parsing | HTML Parser - Part 1 | Problem | Easy | Solution |
| Regex and Parsing | HTML Parser - Part 2 | Problem | Easy | Solution |
| Regex and Parsing | Detect HTML Tags, Attributes and Attribute Values | Problem | Easy | Solution |
| Regex and Parsing | Validating UID | Problem | Easy | Solution |
| Regex and Parsing | Validating Credit Car Numbers | Problem | Medium | Solution |
| Regex and Parsing | Validating Postal Codes | Problem | Hard | Solution |
| Regex and Parsing | Matrix Script | Problem | Hard | Solution |
| XML | XML 1 - Find the Score | Problem | Easy | Solution |
| XML | XML 2 - Find the Maximum Depth | Problem | Easy | Solution |
| Closures and Decorators | Standardize Mobile Number Using Decorators | Problem | Easy | Solution |
| Closures and Decorators | Decorators 2 - Name Directory | Problem | Easy | Solution |
| Numpy | Arrays | Problem | Easy | Solution |
| Numpy | Shape and Reshape | Problem | Easy | Solution |
| Numpy | Transpose and Flatten | Problem | Easy | Solution |
| Numpy | Concatenate | Problem | Easy | Solution |
| Numpy | Zeros and Ones | Problem | Easy | Solution |
| Numpy | Eye and Identity | Problem | Easy | Solution |
| Numpy | Array Mathematics | Problem | Easy | Solution |
| Numpy | Floor, Ceil, and Rint | Problem | Easy | Solution |
| Numpy | Sum and Prod | Problem | Easy | Solution |
| Numpy | Min and Max | Problem | Easy | Solution |
| Numpy | Mean, Var, and Std | Problem | Easy | Solution |
| Numpy | Dot and Cross | Problem | Easy | Solution |
| Numpy | Inner and Outer | Problem | Easy | Solution |
| Numpy | Polynormials | Problem | Easy | Solution |
| Numpy | Linear Algebra | Problem | Easy | Solution |
| Debugging | Words Score | Problem | Medium | Solution |
| Debugging | Default Arguments | Problem | Medium | Solution |
| Subdomain | Challenge | Problem | Difficulty | Solution |
|---|---|---|---|---|
| Introduction | Welcome to Java! | Problem | Easy | Solution |
| Introduction | Java Stdin and Stout I | Problem | Easy | Solution |
| Introduction | Java If-Else | Problem | Easy | Solution |
| Introduction | Java Stdin and Stout II | Problem | Easy | Solution |
| Introduction | Java Output Formatting | Problem | Easy | Solution |
| Introduction | Java Loops I | Problem | Easy | Solution |
| Introduction | Java Loops II | Problem | Easy | Solution |
| Introduction | Java Datatypes | Problem | Easy | Solution |
| Introduction | Java End-of-file | Problem | Easy | Solution |
| Introduction | Java Static Initializer Block | Problem | Easy | Solution |
| Introduction | Java Int to String | Problem | Easy | Solution |
| Introduction | Java Date and Time | Problem | Easy | Solution |
| Introduction | Java Currency Formatter | Problem | Easy | Solution |
| String | Java Strings Introduction | Problem | Easy | Solution |
| String | Java Substring | Problem | Easy | Solution |
| String | Java Substring Comparisons | Problem | Easy | Solution |
| String | Java String Reverse | Problem | Easy | Solution |
| String | Java Anagrams | Problem | Easy | Solution |
| String | Java String Tokens | Problem | Easy | Solution |
| String | Pattern Syntax checker | Problem | Easy | Solution |
| String | Java Regex | Problem | Medium | Solution |
| String | Java Regex 2 - Duplicate Words | Problem | Medium | Solution |
| String | Valid Username regular Expressions | Problem | Easy | Solution |
| String | Tag Content Extractor | Problem | Medium | Solution |
| Big Number | Java BigDecimal | Problem | Medium | Solution |
| Big Number | Java Primality Test | Problem | Easy | Solution |
| Big Number | Java BigInteger | Problem | Easy | Solution |
| Data Structures | Java 1D Array | Problem | Easy | Solution |
| Data Structures | Java 2D Array | Problem | Easy | Solution |
| Data Structures | Java Subarray | Problem | Easy | Solution |
| Data Structures | Java Arraylist | Problem | Easy | Solution |
| Data Structures | Java 1D Array (Part 2) | Problem | Medium | Solution |
| Data Structures | Java List | Problem | Easy | Solution |
| Data Structures | Java Map | Problem | Easy | Solution |
| Data Structures | Java Stack | Problem | Medium | Solution |
| Data Structures | Java Hashset | Problem | Easy | Solution |
| Data Structures | Java Generics | Problem | Easy | Solution |
| Data Structures | Java Compactor | Problem | Medium | Solution |
| Data Structures | Java Sort | Problem | Easy | Solution |
| Data Structures | Java Dequeque | Problem | Medium | Solution |
| Data Structures | Java BitSet | Problem | Easy | Solution |
| Data Structures | Java Priority Queue | Problem | Medium | Solution |
| Object Oriented Programming | Java Inheritance I | Problem | Easy | Solution |
| Object Oriented Programming | Java Inheritance II | Problem | Easy | Solution |
| Object Oriented Programming | Java Abstract Class | Problem | Easy | Solution |
| Object Oriented Programming | Java Interface | Problem | Easy | Solution |
| Object Oriented Programming | Java Method Overriding | Problem | Easy | Solution |
| Object Oriented Programming | Java Method Overriding 2 (Super Keyword) | Problem | Easy | Solution |
| Object Oriented Programming | Java instanceof keyword | Problem | Easy | Solution |
| Object Oriented Programming | Java Iterator | Problem | Easy | Solution |
| Exception Handling | Java Exception Handling (Try-catch) | Problem | Easy | Solution |
| Exception Handling | Java Exception Handling | Problem | Easy | Solution |
| Advanced | Java Varargs - Simple Additio | Problem | Easy | Solution |
| Advanced | Java Reflection - Attributes | Problem | Easy | Solution |
| Advanced | Can You Access? | Problem | Medium | Solution |
| Advanced | Prime Checker | Problem | Medium | Solution |
| Advanced | Java Factory Pattern | Problem | Easy | Solution |
| Advanced | Java Singleton Pattern | Problem | Easy | Solution |
| Advanced | Java Visitor Pattern | Problem | Medium | Solution |
| Advanced | Java Annotations | Problem | Medium | Solution |
| Advanced | Covariant Return Types | Problem | Easy | Solution |
| Advanced | Java Lambda Expressions | Problem | Medium | Solution |
| Advanced | Java MD5 | Problem | Medium | Solution |
| Advanced | Java SHA-256 | Problem | Medium | Solution |
| Subdomain | Challenge | Problem | Difficulty | Solution |
|---|---|---|---|---|
| Introduction | "Hello World" in C | Problem | Easy | Solution |
| Introduction | Playing With Characters | Problem | Easy | Solution |
| Introduction | Sum and Difference of Two Numbers | Problem | Easy | Solution |
| Introduction | Functions in C | Problem | Easy | Solution |
| Introduction | Pointers in C | Problem | Easy | Solution |
| Conditionals and Loops | Conditional Statements in C | Problem | Easy | Solution |
| Conditionals and Loops | For Loop in C | Problem | Easy | Solution |
| Conditionals and Loops | Sum of Digits of a Five Digit Number | Problem | Easy | Solution |
| Conditionals and Loops | Bitwise Operators | Problem | Easy | Solution |
| Conditionals and Loops | Printing Pattern Using Loops | Problem | Medium | Solution |
| Arrays and Strings | 1D Arrays in C | Problem | Medium | Solution |
| Arrays and Strings | Array Reversal | Problem | Medium | Solution |
| Arrays and Strings | Printing Tokens | Problem | Medium | Solution |
| Arrays and Strings | Digit Frequency | Problem | Medium | Solution |
| Arrays and Strings | Dynamic Array in C | Problem | Medium | Solution |
| Functions | Calculate the Nth term | Problem | Easy | Solution |
| Functions | Students Marks Sum | Problem | Easy | Solution |
| Functions | Sorting Array of Strings | Problem | Hard | Solution |
| Functions | Permutations of Strings | Problem | Medium | Solution |
| Functions | Variadic functions in C | Problem | Medium | Solution |
| Functions | Querying the Document | Problem | Hard | Solution |
| Structs and Enums | Boxes through a Tunnel | Problem | Easy | Solution |
| Structs and Enums | Small Triangles, Large Triangles | Problem | Medium | Solution |
| Structs and Enums | Post Transition | Problem | Hard | Solution |
| Structs and Enums | Structuring the Document | Problem | Hard | Solution |
| Subdomain | Challenge | Problem | Difficulty | Solution |
|---|---|---|---|---|
| Basic Select | Reversing the Select Query I | Problem | Easy | # |
| Basic Select | Revising the Select Query II | Problem | Easy | # |
| Basic Select | Select All | Problem | Easy | # |
| Basic Select | Select By ID | Problem | Easy | # |
| Basic Select | Japanese Cities' Attributes | Problem | Easy | # |
| Basic Select | Japanese Cities' Names | Problem | Easy | # |
| Basic Select | Weather Observation Station 1 | Problem | Easy | # |
| Basic Select | Weather Observation Station 3 | Problem | Easy | # |
| Basic Select | Weather Observation Station 4 | Problem | Easy | # |
| Basic Select | Weather Observation Station 5 | Problem | Easy | # |
| Basic Select | Weather Observation Station 6 | Problem | Easy | # |
| Basic Select | Weather Observation Station 7 | Problem | Easy | # |
| Basic Select | Weather Observation Station 8 | Problem | Easy | # |
| Basic Select | Weather Observation Station 9 | Problem | Easy | # |
| Basic Select | Weather Observation Station 10 | Problem | Easy | # |
| Basic Select | Weather Observation Station 11 | Problem | Easy | # |
| Basic Select | Weather Observation Station 12 | Problem | Easy | # |
| Basic Select | Higher Than 75 Marks | Problem | Easy | # |
| Basic Select | Employee Names | Problem | Easy | # |
| Basic Select | Employee Salaries | Problem | Easy | # |
| Advanced Select | Type of Triangle | Problem | Easy | # |
| Advanced Select | Occupations | Problem | Medium | # |
| Advanced Select | Binary Tree Nodes | Problem | Medium | # |
| Advanced Select | New Companies | Problem | Medium | # |
| Aggregation | Revising Aggregations - The Count Function | Problem | Easy | # |
| Aggregation | Revising Aggregations - The Sum Function | Problem | Easy | # |
| Aggregation | Revising Aggregations - Averages | Problem | Easy | # |
| Aggregation | Average Population | Problem | Easy | # |
| Aggregation | Japan Population | Problem | Easy | # |
| Aggregation | Population Density Difference | Problem | Easy | # |
| Aggregation | The Blunder | Problem | Easy | # |
| Aggregation | Top Earners | Problem | Easy | # |
| Aggregation | Weather Observation Station 2 | Problem | Easy | # |
| Aggregation | Weather Observation Station 13 | Problem | Easy | # |
| Aggregation | Weather Observation Station 14 | Problem | Easy | # |
| Aggregation | Weather Observation Station 15 | Problem | Easy | # |
| Aggregation | Weather Observation Station 16 | Problem | Easy | # |
| Aggregation | Weather Observation Station 17 | Problem | Easy | # |
| Aggregation | Weather Observation Station 18 | Problem | Medium | # |
| Aggregation | Weather Observation Station 19 | Problem | Medium | # |
| Aggregation | Weather Observation Station 20 | Problem | Medium | # |
| Subdomain | Challenge | Problem | Difficulty | Solution |
|---|---|---|---|---|
| Arrays | Arrays - DS | Problem | Easy | Solution |
| Arrays | 2D Array - DS | Problem | Easy | Solution |
| Arrays | Dynamic Array | Problem | Easy | Solution |
| Arrays | Left Rotation | Problem | Easy | Solution |
| Arrays | Sparse Arrays | Problem | Medium | Solution |
| Arrays | Array Manipulation | Problem | Hard | Solution |
| Linked Lists | Print the Elements of a Linked Lists | Problem | Easy | Solution |
| Linked Lists | Insert a Node at the Tail of a Linked List | Problem | Easy | Solution |
| Linked Lists | Insert a node at the head of a Linked List | Problem | Easy | Solution |
| Linked Lists | Insert a node at a specific position in a Linked List | Problem | Easy | Solution |
| Linked Lists | Delete a Node | Problem | Easy | Solution |
| Linked Lists | Print in Reverse | Problem | Easy | Solution |
| Linked Lists | Reverse a Linked List | Problem | Easy | Solution |
| Linked Lists | Compare Two Linked Lists | Problem | Easy | Solution |
| Linked Lists | Merge Two Sorted Linked Lists | Problem | Easy | Solution |
| Linked Lists | Get Node Value | Problem | Easy | Solution |
| Linked Lists | Delete Duplicate-value nodes from a Sorted Linked List | Problem | Easy | Solution |
| Linked Lists | Cycle Detection | Problem | Medium | Solution |
| Linked Lists | Find Merge Point of Two Lists | Problem | Easy | Solution |
| Linked Lists | Inserting a Node Into a Sorted Doubly Linked List | Problem | Easy | Solution |
| Linked Lists | Reverse a Doubly Linked List | Problem | Easy | Solution |
| Trees | Tree: Preorder Traversal | Problem | Easy | Solution |
| Trees | Tree: Postorder Traversal | Problem | Easy | Solution |
| Trees | Tree: Inorder Traversal | Problem | Easy | Solution |
| Trees | Tree: Height of a Binary Tree | Problem | Easy | Solution |
| Trees | Tree: Top View | Problem | Easy | Solution |
| Trees | Tree: Level Order Traversal | Problem | Easy | Solution |
| Trees | Binary Search Tree: Insertion | Problem | Easy | Solution |
| Trees | Tree: Huffman Decoding | Problem | Medium | Solution |
| Trees | Binary Search Tree: Loswest Common Ancestor | Problem | Easy | Solution |
| Trees | Kitty's Calculations on a Tree | Problem | Advanced | Solution |
| Trees | Is This a Binary Search Tree | Problem | Medium | Solution |
| Trees | Swap Nodes [Algo] | Problem | Medium | Solution |
| Trees | Balanced Forest | Problem | Hard | Solution |
| Trees | Jenny's Subtrees | Problem | Hard | Solution |
| Trees | Square-Ten Tree | Problem | Hard | Solution |
| Trees | Tree Coordinates | Problem | Expert | Solution |
| Trees | Array Pairs | Problem | Advanced | Solution |
| Balanced Trees | Self Balancing Tree | Problem | Medium | Solution |
| Balanced Trees | Array and Simople Queries | Problem | Hard | Solution |
| Balanced Trees | Median Updates | Problem | Hard | Solution |
| Stacks | Maximum Element | Problem | Easy | Solution |
| Stacks | Balanced Brackets | Problem | Medium | Solution |
| Stacks | Equal Stacks | Problem | Easy | Solution |
| Stacks | Largest Rectangle | Problem | Medium | Solution |
| Stacks | Simple Text Editor | Problem | Medium | Solution |
| Stacks | Game of Two Stacks | Problem | Medium | Solution |
| Stacks | Poisonous Plants | Problem | Hard | Solution |
| Stacks | AND xor OR | Problem | Hard | Solution |
| Stacks | Waiter | Problem | Medium | Solution |
| Queues | Castle on the Grid | Problem | Medium | Solution |
| Queues | Queue using Two Stacks | Problem | Medium | Solution |
| Queues | Down to Zero II | Problem | Medium | Solution |
| Queues | Truck Tour | Problem | Hard | Solution |
| Queues | Queries with Fixed Length | Problem | Hard | Solution |
| Heap | QHEAP1 | Problem | Easy | Solution |
| Heap | Jesse and Cookies | Problem | Easy | Solution |
| Heap | Find the Running Median | Problem | Hard | Solution |
| Heap | Minimum Average Waiting Time | Problem | Hard | Solution |
| Disjoint Set | Merging Communities | Problem | Hard | Solution |
| Disjoint Set | Components in a Graph | Problem | Medium | Solution |
| Disjoint Set | Kundu and Tree | Problem | Hard | Solution |
| Disjoint Set | Super Maximum Cost Queries | Problem | Hard | Solution |
| Multiple Choice | Data Structures MCQ 1 | Problem | Easy | Solution |
| Multiple Choice | Data Structures MCQ 2 | Problem | Easy | Solution |
| Multiple Choice | Data Structures MCQ 3 | Problem | Easy | Solution |
| Trie | Contacts | Problem | Medium | Solution |
| Trie | No Prfix Set | Problem | Hard | Solution |
| Advanced | Kindergarten Adventures | Problem | Medium | Solution |
| Advanced | Cube Summation | Problem | Hard | Solution |
| Advanced | Mr. X and His Shots | Problem | Medium | Solution |
| Advanced | Direct Connections | Problem | Hard | Solution |
| Advanced | Subsequence Weighting | Problem | Advanced | Solution |
| Advanced | Jim and the Skyscrapers | Problem | Medium | Solution |
| Advanced | Palindromic Subsets | Problem | Hard | Solution |
| Advanced | Counting On a Tree | Problem | Expert | Solution |
| Advanced | Polynomial Division | Problem | Hard | Solution |
| Advanced | Costly Intervals | Problem | Hard | Solution |
| Advanced | The Strange Function | Problem | Hard | Solution |
| Advanced | Self-Driving Bus | Problem | Advanced | Solution |
| Advanced | Unique Colors | Problem | Advanced | Solution |
| Advanced | Fibonacci Numbers Tree | Problem | Expert | Solution |
| Advanced | Pair Sums | Problem | Expert | Solution |
| Advanced | Functional Palindromes | Problem | Advanced | Solution |
| Advanced | Lazy White Falcon | Problem | Hard | Solution |
| Advanced | Ticket to Ride | Problem | Expert | Solution |
| Advanced | Heavy Light White Falcon | Problem | Hard | Solution |
| Advanced | Sum of the Maximums | Problem | Advanced | Solution |
| Advanced | Number Game on a Tree | Problem | Expert | Solution |
| Advanced | Heavy Light 2 White Falcon | Problem | Hard | Solution |
| Advanced | Library Query | Problem | Advanced | Solution |
| Advanced | Starfleet | Problem | Advanced | Solution |
| Advanced | Almost Equal - Advanced | Problem | Expert | Solution |
| Advanced | Almost sorted interval | Problem | Expert | Solution |
| Advanced | Burger Happiness | Problem | Hard | Solution |
| Advanced | Roy and alpha-beta trees | Problem | Hard | Solution |
| Advanced | Coloring Tree | Problem | Hard | Solution |
| Advanced | Recalling Early Days GP with Trees | Problem | Hard | Solution |
| Advanced | Swaps and Sum | Problem | Advanced | Solution |
| Advanced | Arithmetic Progressions | Problem | Advanced | Solution |
| Advanced | Coolguy and Two Subsequences | Problem | Advanced | Solution |
| Advanced | White Falcon And Tree | Problem | Hard | Solution |
| Advanced | Subtrees And Paths | Problem | Advanced | Solution |
| Advanced | Triplets | Problem | Advanced | Solution |
| Advanced | Beautiful Segments | Problem | Expert | Solution |
| Advanced | Divisibility | Problem | Expert | Solution |
| Advanced | BST maintenance | Problem | Advanced | Solution |
| Advanced | Find Maximum Index Product | Problem | Medium | Solution |
| Advanced | Taxicab Driver's Problem | Problem | Advanced | Solution |
| Advanced | Jaggu Playing with Balloons | Problem | Advanced | Solution |
| Advanced | Dynamic Summation | Problem | Hard | Solution |
| Advanced | Two Array Problem | Problem | Hard | Solution |
| Advanced | Rooted Tree | Problem | Hard | Solution |
| Advanced | The crazy helix | Problem | Advanced | Solution |
| Advanced | Network administration | Problem | Hard | Solution |
| Advanced | Easy Addition | Problem | Expert | Solution |
| Advanced | Find the permutation | Problem | Expert | Solution |
| Advanced | Company Retreat | Problem | Advanced | Solution |
| Advanced | Box Operations | Problem | Expert | Solution |
| Advanced | Max Transform | Problem | Expert | Solution |
| Advanced | Array and Queries | Problem | Hard | Solution |
| Subdomain | Challenge | Problem | Difficulty | Solution |
|---|---|---|---|---|
| Warmup | Solve Me First | Problem | Easy | # |
| Warmup | Simple Array Sum | Problem | Easy | # |
| Warmup | Compare the Triplets | Problem | Easy | Solution |
| Warmup | A Very Big Sum | Problem | Easy | Solution |
| Warmup | Diagonal Difference | Problem | Easy | Solution |
| Warmup | Plus Minus | Problem | Easy | Solution |
| Warmup | Staircase | Problem | Easy | Solution |
| Warmup | Min-Max Sum | Problem | Easy | Solution |
| Warmup | Birthday Cake Candles | Problem | Easy | Solution |
| Warmup | Time Conversion | Problem | Easy | Solution |
| Implementation | Grading Students | Problem | Easy | Solution |
| Implementation | Apple and Orange | Problem | Easy | Solution |
| Implementation | Number Line Jumps | Problem | Easy | Solution |
| Implementation | Between Two Sets | Problem | Easy | Solution |
| Implementation | Breaking the Records | Problem | Easy | Solution |
| Implementation | Subarray Division | Problem | Easy | Solution |
| Implementation | Divisible Sum Pairs | Problem | Easy | Solution |
| Implementation | Migratory Birds | Problem | Easy | Solution |
| Implementation | Day of the Programmer | Problem | Easy | Solution |
| Implementation | Bill Division | Problem | Easy | Solution |
| Implementation | Sales by Match | Problem | Easy | Solution |
| Implementation | Drawing Book | Problem | Easy | Solution |
| Implementation | Counting Valleys | Problem | Easy | Solution |
| Implementation | Electronics Shop | Problem | Easy | Solution |
| Implementation | Cats and a Mouse | Problem | Easy | Solution |
| Implementation | Forming a Magic Square | Problem | Medium | Solution |
| Implementation | Picking Numbers | Problem | Easy | # |
| Implementation | Climbing the Leaderboard | Problem | Medium | Solution |
| Implementation | The Hurdle Race | Problem | Easy | Solution |
| Implementation | Designer PDF Viewer | Problem | Easy | # |
| Implementation | Utopian Tree | Problem | Easy | Solution |
| Implementation | Angry Professor | Problem | Easy | Solution |
| Implementation | Beautiful Days at the Movies | Problem | Easy | Solution |
| Implementation | Viral Advertising | Problem | Easy | Solution |
| Implementation | Save the Prisoner! | Problem | Easy | Solution |
| Implementation | Circular Array Rotation | Problem | Easy | Solution |
| Implementation | Sequence Equation | Problem | Easy | Solution |
| Implementation | Jumping on the Clouds: Revisited | Problem | Easy | Solution |
| Implementation | Find Digits | Problem | Easy | Solution |
| Implementation | Extra Long Factorials | Problem | Medium | # |
| Implementation | Append and Delete | Problem | Easy | Solution |
| Implementation | Sherlock and Squares | Problem | Easy | Solution |
| Implementation | Library Fine | Problem | Easy | # |
| Implementation | Cut the sticks | Problem | Easy | Solution |
| Implementation | Non-Divisible Subset | Problem | Medium | # |
| Implementation | Repeated String | Problem | Easy | Solution |
| Implementation | Jumping on the Clouds | Problem | Easy | # |
| Implementation | Equalize the Array | Problem | Easy | Solution |
| Implementation | Queen's Attack II | Problem | Medium | # |
| Implementation | ACM ICPC Team | Problem | Easy | Solution |
| Implementation | Taum and B'day | Problem | Easy | # |
| Implementation | Organizing Containers of Balls | Problem | Medium | Solution |
| Implementation | Encryption | Problem | Medium | # |
| Implementation | Bigger is Greater | Problem | Medium | Solution |
| Implementation | Modified Kaprekar Numbers | Problem | Easy | Solution |
| Implementation | Beautiful Triplets | Problem | Easy | Solution |
| Implementation | Minimum Distances | Problem | Easy | Solution |
| Implementation | Halloween Sale | Problem | Easy | Solution |
| Implementation | The Time in Words | Problem | Medium | # |
| Implementation | Chocolate Feast | Problem | Easy | Solution |
| Implementation | Service Lane | Problem | Easy | Solution |
| Implementation | Lisa's Workbook | Problem | Easy | Solution |
| Implementation | Flatland Space Stations | Problem | Easy | Solution |
| Implementation | Fair Rations | Problem | Easy | Solution |
| Implementation | Cavity Map | Problem | Easy | Solution |
| Implementation | Manasa and Stones | Problem | Easy | Solution |
| Implementation | The Grid Search | Problem | Medium | # |
| Implementation | Happy Ladybugs | Problem | Easy | Solution |
| Implementation | Strange Counter | Problem | Easy | Solution |
| Implementation | 3D Surface Area | Problem | Medium | Solution |
| Implementation | Absolute Permutation | Problem | Medium | # |
| Implementation | The Bomberman Game | Problem | Medium | # |
| Implementation | Ema's Supercomputer | Problem | Medium | # |
| Implementation | Larry's Array | Problem | Medium | Solution |
| Implementation | Almost Sorted | Problem | Medium | # |
| Implementation | Matrix Layer Rotation | Problem | Hard | # |
| Strings | CamelCase | Problem | Easy | Solution |
| Strings | Strong Password | Problem | Easy | Solution |
| Strings | Super Reduced String | Problem | Easy | Solution |
| Strings | Two Characters | Problem | Easy | Solution |
| Strings | Caesar Cipher | Problem | Easy | Solution |
| Strings | Mars Exploration | Problem | Easy | Solution |
| Strings | HckerRank in a String! | Problem | Easy | Solution |
| Strings | Pangrams | Problem | Easy | Solution |
| Strings | Weighted Uniform Strings | Problem | Easy | Solution |
| Strings | Separate the Number | Problem | Easy | Solution |
| Strings | Funny String | Problem | Easy | Solution |
| Strings | Gemstones | Problem | Easy | Solution |
| Strings | Alternating Characters | Problem | Easy | Solution |
| Strings | Beautiful Binary String | Problem | Easy | # |
| Strings | The Love-Letter Mystery | Problem | Easy | Solution |
| Strings | Determining DNA Health | Problem | Hard | Solution |
| Strings | Palindrome Index | Problem | Easy | Solution |
| Strings | Anagram | Problem | Easy | Solution |
| Strings | Making Anagrams | Problem | Easy | Solution |
| Strings | Game of Thrones - I | Problem | Easy | Solution |
| Strings | Two Strings | Problem | Easy | Solution |
| Strings | String Construction | Problem | Easy | Solution |
| Strings | Sherlock and the Valid String | Problem | Medium | Solution |
| Strings | Highest Value Palindrome | Problem | Medium | Solution |
| Strings | Maximum Palidrome | Problem | Medium | Solution |
| Strings | Sherlock and Anagrams | Problem | Medium | # |
| Strings | Common Child | Problem | Medium | # |
| Strings | Bear and Steady Gene | Problem | Medium | # |
| Strings | Morgan and a String | Problem | Expert | Solution |
| Strings | Cout Strings | Problem | Hard | # |
| Strings | String Function Calculation | Problem | Advanced | Solution |
| Strings | Build a Palindrome | Problem | Advanced | Solution |
| Strings | Build a String | Problem | Hard | # |
| Strings | Gridland Provinces | Problem | Hard | Solution |
| Strings | Cards Permutation | Problem | Expert | Solution |
| Strings | Ashton and String | Problem | Advanced | Solution |
| Strings | String Similarity | Problem | Expert | Solution |
| Strings | Super Functional Strings | Problem | Advanced | Solution |
| Strings | Circular Palindromes | Problem | Advanced | Solution |
| Strings | Similar Strings | Problem | Advanced | # |
| Strings | Save Humanity | Problem | Expert | Solution |
| Strings | Find Strings | Problem | Expert | Solution |
| Strings | Palindromic Border | Problem | Expert | Solution |
| Strings | Two Two | Problem | Advanced | Solution |
| Strings | Two Strings Game | Problem | Expert | Solution |
| Strings | Letter Islands | Problem | Expert | Solution |
| Strings | Pseudo-Isomorphic Substrings | Problem | Expert | # |
| Strings | How Many Substrings? | Problem | Expert | Solution |
| Sorting | Big Sorting | Problem | Easy | Solution |
| Sorting | Intro to Tutorial Challenges | Problem | Easy | Solution |
| Sorting | Insertion Sort - Part 1 | Problem | Easy | Solution |
| Sorting | Insertion Sort - Part 2 | Problem | Easy | Solution |
| Sorting | Correctness and the Loop Invariant | Problem | Easy | Solution |
| Sorting | Running Time of Algorithms | Problem | Easy | Solution |
| Sorting | Quicksort 1 - Partition | Problem | Easy | Solution |
| Sorting | Counting Sort 1 | Problem | Easy | Solution |
| Sorting | Counting Sort 2 | Problem | Easy | Solution |
| Sorting | The Full Counting Sort | Problem | Medium | Solution |
| Sorting | Closest Numbers | Problem | Easy | Solution |
| Sorting | Find the Median | Problem | Easy | Solution |
| Sorting | Insertion Sort Advanced Analysis | Problem | Advanced | Solution |
| Sorting | Fraudulent Activity Notifications | Problem | Medium | Solution |
| Sorting | Lily's Homework | Problem | Medium | # |
| Search | Hackerland Radio Transmitters | Problem | Medium | Solution |
| Search | Gridland Metro | Problem | Medium | Solution |
| Search | Ice Cream Parlor | Problem | Easy | Solution |
| Search | KnightL on a Shessboard | Problem | Medium | # |
| Search | Minimum Loss | Problem | Medium | Solution |
| Search | Missing Numbers | Problem | Easy | Solution |
| Search | Pairs | Problem | Medium | # |
| Search | Sherlock and Array | Problem | Easy | Solution |
| Search | Maximum Subarray Sum | Problem | Hard | Solution |
| Search | Connected Cells in a Grid | Problem | Medium | # |
| Search | Short Palindrome | Problem | Medium | Solution |
| Search | Maximizong Mission Points | Problem | Hard | Solution |
| Search | Count Luck | Problem | Medium | # |
| Search | Cut the Tree | Problem | Medium | # |
| Search | Making Candies | Problem | Hard | # |
| Search | Gena Playing Hanoi | Problem | Medium | # |
| Search | Beautiful Quadruples | Problem | Medium | # |
| Search | Red Kight;s Shortest Path | Problem | Medium | # |
| Search | Bike Racers | Problem | Hard | # |
| Search | Task Scheduling | Problem | Advanced | # |
| Search | Similar Pair | Problem | Advanced | # |
| Search | Absolute Element Sum | Problem | Hard | Solution |
| Search | Almost Integer Rock Garden | Problem | Expert | Solution |
| Search | Sorted Subsegments | Problem | Hard | # |
| Search | Distant Pairs | Problem | Expert | # |
| Search | King Richard's Kinghts | Problem | Hard | # |
| Graph Theory | Fog in Maze | Problem | Hard | # |
| Graph Theory | Roads and Libraries | Problem | Medium | Solution |
| Graph Theory | Journey to the Moon | Problem | Medium | Solution |
| Graph Theory | Synchronous Shopping | Problem | Medium | Solution |
| Graph Theory | Subset Component | Problem | Hard | Solution |
| Graph Theory | Breadth First Search: Shortest Reach | Problem | Medium | # |
| Graph Theory | Kruskal (MST): Really Special Subtree | Problem | Medium | Solution |
| Graph Theory | Even Tree | Problem | Medium | Solution |
| Graph Theory | Snakes and Ladders: The Quickest Way Up | Problem | Medium | Solution |
| Graph Theory | Dijkstra: Shortest Reach 2 | Problem | Hard | # |
| Graph Theory | The Story of a Tree | Problem | Medium | # |
| Graph Theory | Prim's(MST): Special Subtree | Problem | Medium | Solution |
| Graph Theory | Toll Cost Digits | Problem | Hard | # |
| Graph Theory | Real Estate Broker | Problem | Hard | # |
| Graph Theory | Clique | Problem | Medium | # |
| Graph Theory | Minimum Penalty Path | Problem | Medium | # |
| Graph Theory | Demanding Money | Problem | Hard | Solution |
| Graph Theory | The Value of Friendship | Problem | Hard | # |
| Graph Theory | Coprime Paths | Problem | Expert | Solution |
| Graph Theory | Minimum MST Graph | Problem | Expert | # |
| Graph Theory | Jack goes to Rapture | Problem | Medium | # |
| Graph Theory | Crab Graphs | Problem | Medium | # |
| Graph Theory | Bead Ornaments | Problem | Advanced | Solution |
| Graph Theory | Jeanie's Route | Problem | Medium | # |
| Graph Theory | Floyd: City of Blinding Light | Problem | Hard | # |
| Graph Theory | Roads in HackerLand | Problem | Medium | # |
| Graph Theory | Kingdom Connectivity | Problem | Medium | # |
| Graph Theory | Computer Game | Problem | Hard | # |
| Graph Theory | Rust & Murderer | Problem | Medium | # |
| Graph Theory | Problem solving | Problem | Hard | # |
| Graph Theory | Journey Scheduling | Problem | Hard | # |
| Graph Theory | Matrix | Problem | Hard | # |
| Graph Theory | Recording Episodes | Problem | Hard | # |
| Graph Theory | Repair Roads | Problem | Hard | # |
| Graph Theory | Kth Ancestor | Problem | Hard | # |
| Graph Theory | ByteLandian Tours | Problem | Hard | # |
| Graph Theory | Find the Path | Problem | Hard | # |
| Graph Theory | Savita and Friends | Problem | Hard | # |
| Graph Theory | Liars | Problem | Advanced | # |
| Graph Theory | Jumping Rooks | Problem | Advanced | # |
| Graph Theory | Tripartite Matching | Problem | Hard | # |
| Graph Theory | Tree Flow | Problem | Hard | # |
| Graph Theory | DAG Queries | Problem | Expert | # |
| Graph Theory | Favorite sequence | Problem | Advanced | # |
| Graph Theory | Jogging Cats | Problem | Advanced | # |
| Graph Theory | Quadrant Quieries | Problem | Advanced | # |
| Graph Theory | Hacker Country | Problem | Hard | # |
| Graph Theory | HackerX | Problem | Hard | # |
| Graph Theory | Huarongdao | Problem | Expert | # |
| Graph Theory | Training the Army | Problem | Hard | # |
| Graph Theory | Jim and His LAN Party | Problem | Hard | # |
| Graph Theory | Travel in HackerLand | Problem | Hard | # |
| Graph Theory | Alex vs Fedor | Problem | Expert | # |
| Graph Theory | Vertical Paths | Problem | Expert | # |
| Graph Theory | Drive | Problem | Expert | # |
| Graph Theory | Travelling Salesman in a Grid | Problem | Expert | # |
| Graph Theory | Road Network | Problem | Expert | # |
| Graph Theory | Going to the Office | Problem | Expert | # |
| Graph Theory | Tree Splitting | Problem | Advanced | # |
| Graph Theory | Ticket | Problem | Expert | # |
| Graph Theory | DFS Edges | Problem | Expert | # |
| Graph Theory | Diameter Minimization | Problem | Expert | # |
| Graph Theory | Airports | Problem | Expert | # |
| Graph Theory | Definite Random Walks | Problem | Expert | # |
| Greedy | Marc's Cakewalk | Problem | Easy | Solution |
| Greedy | Minimum Absolute Difference in an Array | Problem | Medium | Solution |
| Greedy | Grid Challenge | Problem | Easy | Solution |
| Greedy | Luck Balance | Problem | Easy | Solution |
| Greedy | Maximum Perimeter Triangle | Problem | Easy | Solution |
| Greedy | Beautiful Pairs | Problem | Easy | Solution |
| Greedy | Candies | Problem | Medium | # |
| Greedy | Sherlock and the Beast | Problem | Easy | Solution |
| Greedy | Priyanka and Toys | Problem | Easy | Solution |
| Greedy | Largest Permutation | Problem | Easy | Solution |
| Greedy | Mark and Toys | Problem | Easy | Solution |
| Greedy | Greedy Florist | Problem | Medium | Solution |
| Greedy | Max Min | Problem | Medium | Solution |
| Greedy | Jim and the Orders | Problem | Easy | Solution |
| Greedy | Permuting Two Arrays | Problem | Easy | Solution |
| Greedy | Cutting Boards | Problem | Hard | # |
| Greedy | Reverse Shuffle Merge | Problem | Advanced | # |
| Greedy | Goodland Electricity | Problem | Medium | # |
| Greedy | Cloudy Day | Problem | Medium | Solution |
| Greedy | Chief Hopper | Problem | Hard | # |
| Greedy | Sherlock and MiniMax | Problem | Hard | # |
| Greedy | Accessory Collection | Problem | Hard | # |
| Greedy | Team Formation | Problem | Advanced | # |
| Greedy | Fighting Pits | Problem | Hard | # |
| Dynamic Programming | The Coin Change Problem | Problem | Medium | # |
| Dynamic Programming | Equal | Problem | Medium | # |
| Dynamic Programming | Sherlock and Cost | Problem | Medium | Solution |
| Dynamic Programming | Construct the Array | Problem | Medium | # |
| Dynamic Programming | Kingdom Division | Problem | Medium | # |
| Dynamic Programming | Sam and substrings | Problem | Medium | # |
| Dynamic Programming | Fibonacci Modified | Problem | Medium | Solution |
| Dynamic Programming | Abbreviation | Problem | Medium | Solution |
| Dynamic Programming | Prime XOR | Problem | Medium | Solution |
| Dynamic Programming | Decibinary Numbers | Problem | Hard | # |
| Dynamic Programming | Fair Cut | Problem | Medium | # |
| Dynamic Programming | The Maximum Subarray | Problem | Medium | # |
| Dynamic Programming | Angry Children 2 | Problem | Hard | # |
| Dynamic Programming | Sherlock's Array Merging Algorithm | Problem | Hard | # |
| Dynamic Programming | Prime Digit Sums | Problem | Medium | # |
| Dynamic Programming | HackerRank City | Problem | Medium | # |
| Dynamic Programming | Summing Pieces | Problem | Medium | # |
| Dynamic Programming | Mr K marsh | Problem | Medium | # |
| Dynamic Programming | Substring Diff | Problem | Medium | # |
| Dynamic Programming | Xor and Sum | Problem | Medium | # |
| Dynamic Programming | Lego Blocks | Problem | Medium | # |
| Dynamic Programming | Brick Tiling | Problem | Hard | # |
| Dynamic Programming | Alien Languages | Problem | Hard | # |
| Dynamic Programming | Stock Maximize | Problem | Medium | Solution |
| Dynamic Programming | Two Robots | Problem | Medium | Solution |
| Dynamic Programming | Cut Tree | Problem | Medium | Solution |
| Dynamic Programming | Tara's Beautiful Permutations | Problem | Hard | # |
| Dynamic Programming | Wet Shark and Two Subsequences | Problem | Medium | # |
| Dynamic Programming | Mikita and the Game | Problem | Medium | Solution |
| Dynamic Programming | Choosing White Balls | Problem | Hard | # |
| Dynamic Programming | Mandragora Forest | Problem | Medium | # |
| Dynamic Programming | Red John is Back | Problem | Medium | # |
| Dynamic Programming | LCS returns | Problem | Medium | # |
| Dynamic Programming | Grid Waling | Problem | Medium | # |
| Dynamic Programming | Matrix Land | Problem | Hard | # |
| Dynamic Programming | Knapsack | Problem | Medium | # |
| Dynamic Programming | Bricks Game | Problem | Medium | # |
| Dynamic Programming | The Longest Increasing Subsequence | Problem | Advanced | # |
| Dynamic Programming | Coin on the Table | Problem | Medium | # |
| Dynamic Programming | The Longest Common Subsequence | Problem | Medium | # |
| Dynamic Programming | Play with words | Problem | Medium | # |
| Dynamic Programming | Black and White Tree | Problem | Hard | # |
| Dynamic Programming | Coutning Special Sub-Cubes | Problem | Medium | # |
| Dynamic Programming | Interval Selection | Problem | Medium | # |
| Dynamic Programming | String Reduction | Problem | Hard | # |
| Dynamic Programming | Far Vertices | Problem | Hard | # |
| Dynamic Programming | Counting Road Networks | Problem | Expert | # |
| Dynamic Programming | Superman Celebrates Diwali | Problem | Hard | # |
| Dynamic Programming | Hexagonal Grid | Problem | Hard | # |
| Dynamic Programming | Queens on Board | Problem | Hard | # |
| Dynamic Programming | Shashank and the Palindromic Strings | Problem | Advanced | # |
| Dynamic Programming | Points in a Plane | Problem | Advanced | Solution |
| Dynamic Programming | Turn Off the Lights | Problem | Hard | Solution |
| Dynamic Programming | Animal Transport | Problem | Hard | Solution |
| Dynamic Programming | The Indian Job | Problem | Medium | SolutionPrepare_Algorithms_DynamicProgramming_TheIndianJob.py |
| Dynamic Programming | Requirement | Problem | Advanced | # |
| Dynamic Programming | A Super Hero | Problem | Hard | # |
| Dynamic Programming | Clues on a Binary Path | Problem | Hard | # |
| Dynamic Programming | Road Maintenance | Problem | Hard | # |
| Dynamic Programming | Billboards | Problem | Advanced | # |
| Dynamic Programming | Beautiful Strings | Problem | Hard | # |
| Dynamic Programming | Covering the Stains | Problem | Hard | # |
| Dynamic Programming | GCD Matrix | Problem | Hard | # |
| Dynamic Programming | Fairy Chess | Problem | Advanced | # |
| Dynamic Programming | Suffix Rotation | Problem | Expert | # |
| Dynamic Programming | New Year Present | Problem | Hard | # |
| Dynamic Programming | Travel Around The World | Problem | Medium | # |
| Dynamic Programming | Longest Palindromic Subsequence | Problem | Hard | # |
| Dynamic Programming | Candles Counting | Problem | Medium | # |
| Dynamic Programming | Hyper Strings | Problem | Advanced | # |
| Dynamic Programming | Swap Permutation | Problem | Medium | # |
| Dynamic Programming | Extremum Permutations | Problem | Medium | # |
| Dynamic Programming | Square Subsequences | Problem | Hard | # |
| Dynamic Programming | Dorsey Thief | Problem | Advanced | # |
| Dynamic Programming | Minning | Problem | Advanced | # |
| Dynamic Programming | Police Operation | Problem | Hard | # |
| Dynamic Programming | Zurikela's Graph | Problem | Hard | # |
| Dynamic Programming | Modify the Sequence | Problem | Advanced | # |
| Dynamic Programming | Longest Mod Path | Problem | Hard | # |
| Dynamic Programming | P-sequences | Problem | Hard | # |
| Dynamic Programming | Robot | Problem | Advanced | # |
| Dynamic Programming | Lucky Numbers | Problem | Expert | # |
| Dynamic Programming | Unfair Game | Problem | Advanced | # |
| Dynamic Programming | Oil Well | Problem | Hard | # |
| Dynamic Programming | Find the Seed | Problem | Advanced | # |
| Dynamic Programming | The Blacklist | Problem | Advanced | # |
| Dynamic Programming | Tree Pruning | Problem | Advanced | # |
| Dynamic Programming | Ones and Twos | Problem | Hard | # |
| Dynamic Programming | Count Scorecards | Problem | Expert | # |
| Dynamic Programming | Vim War | Problem | Advanced | # |
| Dynamic Programming | Best Spot | Problem | Advanced | # |
| Dynamic Programming | Divisible Numbers | Problem | Expert | # |
| Dynamic Programming | Unique Divide and Conquer | Problem | Advanced | # |
| Dynamic Programming | King and Four Sons | Problem | Expert | # |
| Dynamic Programming | Dortmund Dilemma | Problem | Advanced | # |
| Dynamic Programming | Super Kth LIS | Problem | Advanced | # |
| Dynamic Programming | Counting the Ways | Problem | Expert | # |
| Dynamic Programming | Hard Disk Drives | Problem | Expert | # |
| Dynamic Programming | Separate the Chocolate | Problem | Expert | # |
| Constructive Algorithms | Lena Sort | Problem | Medium | # |
| Constructive Algorithms | Flipping the Matrix | Problem | Medium | # |
| Constructive Algorithms | Gaming Array | Problem | Medium | # |
| Constructive Algorithms | New Year Chaos | Problem | Medium | # |
| Constructive Algorithms | Bonetrousle | Problem | Medium | # |
| Constructive Algorithms | Yet Another KMP Problem | Problem | Hard | # |
| Constructive Algorithms | Beautiful 3 Set | Problem | Hard | Solution |
| Constructive Algorithms | Two Subarrays | Problem | Expert | # |
| Constructive Algorithms | Inverse RMQ | Problem | Hard | # |
| Constructive Algorithms | Lovely Triplets | Problem | Advanced | # |
| Constructive Algorithms | Array Construction | Problem | Advanced | # |
| Bit Manipulation | Lonely Integer | Problem | Easy | Solution |
| Bit Manipulation | Maximizing XOR | Problem | Easy | # |
| Bit Manipulation | Counter Game | Problem | Medium | # |
| Bit Manipulation | Xor-sequence | Problem | Medium | # |
| Bit Manipulation | Sum vs XOR | Problem | Easy | Solution |
| Bit Manipulation | The Great XOR | Problem | Medium | # |
| Bit Manipulation | Flipping bits | Problem | Easy | Solution |
| Bit Manipulation | Yet Another Minimax Problem | Problem | Medium | # |
| Bit Manipulation | Sansa and XOR | Problem | Medium | # |
| Bit Manipulation | AND Product | Problem | Medium | # |
| Bit Manipulation | Winning Lottery Ticket | Problem | Medium | # |
| Bit Manipulation | Xoring Ninja | Problem | Hard | # |
| Bit Manipulation | Cipher | Problem | Medium | # |
| Bit Manipulation | XOR Matrix | Problem | Hard | # |
| Bit Manipulation | What's Next? | Problem | Medium | # |
| Bit Manipulation | String Transmission | Problem | Hard | # |
| Bit Manipulation | A or B | Problem | Medium | # |
| Bit Manipulation | Manipulative Numbers | Problem | Hard | # |
| Bit Manipulation | Stone Game | Problem | Hard | # |
| Bit Manipulation | 2's complement | Problem | Advanced | # |
| Bit Manipulation | Changing Bits | Problem | Advanced | # |
| Bit Manipulation | XOR Key | Problem | Advanced | # |
| Bit Manipulation | Maximizing the Function | Problem | Hard | # |
| Bit Manipulation | XOR Subsequences | Problem | Advanced | # |
| Bit Manipulation | Iterate It | Problem | Expert | # |
| Bit Manipulation | Hamming Distance | Problem | Expert | # |
| Bit Manipulation | Mixing Proteins | Problem | Hard | # |
| Recursion | The Power Sum | Problem | Medium | # |
| Recursion | Crossword Puzzle | Problem | Medium | # |
| Recursion | Recursive Digit Sum | Problem | Medium | # |
| Recursion | Simplified Chess Engine | Problem | Medium | # |
| Recursion | Password Cracker | Problem | Medium | # |
| Recursion | Arithmetic Expressions | Problem | Hard | # |
| Recursion | Stone Division, Revisited | Problem | Medium | # |
| Recursion | K Factorization | Problem | Hard | # |
| Recursion | Bowling Pins | Problem | Hard | # |
| Recursion | Simplified Chess Engine II | Problem | Hard | # |
| Recursion | Repetitive K-Sums | Problem | Advanced | # |
| Game Theory | Game of Stones | Problem | Easy | Solution |
| Game Theory | Tower Breakers | Problem | Easy | Solution |
| Game Theory | A Chessboard Game | Problem | Easy | Solution |
| Game Theory | Introduction to Nim Game | Problem | Easy | Solution |
| Game Theory | Misere Nim | Problem | Easy | Solution |
| Game Theory | Nimble Game | Problem | Easy | Solution |
| Game Theory | Alice and Bob's Silly Game | Problem | Medium | # |
| Game Theory | Poker Nim | Problem | Easy | Solution |
| Game Theory | Tower Breakers, Revisited | Problem | Medium | # |
| Game Theory | Tower Breakers, Again! | Problem | Medium | # |
| Game Theory | Zero-Move Nim | Problem | Medium | # |
| Game Theory | Chessboard Game, Again! | Problem | Medium | # |
| Game Theory | Digits Square Board | Problem | Medium | # |
| Game Theory | Fun Game | Problem | Medium | # |
| Game Theory | Stone Division | Problem | Hard | # |
| Game Theory | Chocolate in Box | Problem | Medium | # |
| Game Theory | Kitty and Katty | Problem | Medium | # |
| Game Theory | Powers Game | Problem | Medium | # |
| Game Theory | Deforestation | Problem | Medium | # |
| Game Theory | Bob and Ben | Problem | Medium | # |
| Game Theory | Tower Breakers - The Final Battle | Problem | Medium | # |
| Game Theory | Simple Game | Problem | Hard | # |
| Game Theory | Permutation Game | Problem | Medium | # |
| Game Theory | Move the Coins | Problem | Hard | # |
| Game Theory | Play on Bender | Problem | Medium | # |
| Game Theory | New Year Game | Problem | Medium | # |
| Game Theory | Stone Piles | Problem | Hard | # |
| Game Theory | Chocolate Game | Problem | Hard | # |
| Game Theory | The Prime Game | Problem | Hard | # |
| Game Theory | Vertical Rooks | Problem | Medium | # |
| Game Theory | A Stones Game | Problem | Medium | # |
| Game Theory | Tastes Like Winning | Problem | Expert | # |
| NP Complete | Walking the Approximate Longest Path | Problem | Hard | # |
| NP Complete | Sam's Puzzle (Approximate) | Problem | Advanced | # |
| NP Complete | Spies, Revised | Problem | Expert | # |
| NP Complete | TBS Problem | Problem | Expert | # |
| Debugging | Prime Dates | Problem | Medium | Solution |
| Debugging | Minimum Operations | Problem | Medium | Solution |
| Debugging | XOR Strings | Problem | Easy | Solution |
| Debugging | Zig Zag Sequence | Problem | Medium | Solution |
| Debugging | Smart Number | Problem | Easy | Solution |
| Day | Challenge | Problem | Difficulty | Solution |
|---|---|---|---|---|
| 0 | Hello, World! | Problem | Easy | Solution |
| 0 | Data Types | Problem | Easy | Solution |
| 1 | Arithmetic Operators | Problem | Easy | Solution |
| 1 | Functions | Problem | Easy | Solution |
| 1 | Let and Const | Problem | Easy | Solution |
| 2 | Conditional Statements - If-Else | Problem | Easy | Solution |
| 2 | Conditional Statements - Switch | Problem | Easy | Solution |
| 2 | Loops | Problem | Easy | Solution |
| 3 | Arrays | Problem | Easy | Solution |
| 3 | Try, Catch, and Finally | Problem | Easy | Solution |
| 3 | Throw | Problem | Easy | Solution |
| 4 | Create a Rectangle Object | Problem | Easy | Solution |
| 4 | Count Objects | Problem | Easy | Solution |
| 4 | Classes | Problem | Easy | Solution |
| 5 | Inheritance | Problem | Easy | Solution |
| 5 | Template Literals | Problem | Easy | Solution |
| 5 | Arrow Functions | Problem | Easy | Solution |
| 6 | Bitwise Operators | Problem | Easy | Solution |
| 6 | JavaScript Dates | Problem | Easy | Solution |
| 7 | Regular Expressions I | Problem | Easy | Solution |
| 7 | Regular Expressions II | Problem | Easy | Solution |
| 7 | Regular Expressions III | Problem | Easy | Solution |
| 8 | Create a Button | Problem | Easy | Solution |
| 8 | Buttons Container | Problem | Easy | Solution |
| 9 | Binary Calculator | Problem | Medium | Solution |
| Day | Challenge | Problem | Difficulty | Solution |
|---|---|---|---|---|
| 0 | Mean, Median, and Mode | Problem | Easy | Solution |
| 0 | Weighted Mean | Problem | Easy | Solution |
| 1 | Quartiles | Problem | Easy | Solution |
| 1 | Interquartile Range | Problem | Easy | # |
| 1 | Standard Deviation | Problem | Easy | # |
| 2 | Basic Probability | Problem | Easy | Solution |
| 2 | More Dice | Problem | Easy | Solution |
| 2 | Compound Event Probability | Problem | Easy | # |
| 3 | Conditional Probability | Problem | Easy | # |
| 3 | Cards of the Same Suit | Problem | Easy | # |
| 3 | Drawing Marbles | Problem | Easy | # |
| 4 | Binomial Distribution I | Problem | Easy | # |
| 4 | Binomial Distribution II | Problem | Easy | # |
| 4 | Geometric Distribution I | Problem | Easy | # |
| 4 | Geometric Distribution II | Problem | Easy | # |
| 5 | Poisson Distribution I | Problem | Easy | # |
| 5 | Poisson Distribution II | Problem | Easy | # |
| 5 | Normal Distribution I | Problem | Easy | # |
| 5 | Normal Distribution II | Problem | Easy | # |
| 6 | The Central Limit Theorem I | Problem | Easy | Solution |
| 6 | The Central Limit Theorem II | Problem | Easy | # |
| 6 | The Central Limit Theorem III | Problem | Easy | # |
| 7 | Pearson Correlation Coefficient I | Problem | Easy | # |
| 7 | Spearman's Rank Correlation Coefficient | Problem | Easy | # |
| 8 | Least Square Regression Line | Problem | Easy | # |
| 8 | Pearson Correlation Coefficient II | Problem | Easy | # |
| 9 | Multiple Linear Regression | Problem | Medium | # |
| Day | Challenge | Problem | Difficulty | Solution |
|---|---|---|---|---|
| 0 | Hello, World | Problem | Easy | Solution |
| 1 | Data Types | Problem | Easy | Solution |
| 2 | Operators | Problem | Easy | Solution |
| 3 | Intro to Conditional Statements | Problem | Easy | Solution |
| 4 | Class vs. Instance | Problem | Easy | Solution |
| 5 | Loops | Problem | Easy | Solution |
| 6 | Let's Review | Problem | Easy | Solution |
| 7 | Arrays | Problem | Easy | Solution |
| 8 | Dictionaries and Maps | Problem | Easy | Solution |
| 9 | Recursion 3 | Problem | Easy | Solution |
| 10 | Binary Numbers | Problem | Easy | Solution |
| 11 | 2D Arrays | Problem | Easy | Solution |
| 12 | Inheritance | Problem | Easy | Solution |
| 13 | Abstract Classes | Problem | Easy | Solution |
| 14 | Scope | Problem | Easy | Solution |
| 15 | Linked List | Problem | Easy | Solution |
| 16 | Exceptions - String to Integer | Problem | Easy | Solution |
| 17 | More Exceptions | Problem | Easy | Solution |
| 18 | Queues and Stack | Problem | Easy | Solution |
| 19 | Interfaces | Problem | Easy | Solution |
| 20 | Sorting | Problem | Easy | Solution |
| 21 | Generics | Problem | Easy | Solution |
| 22 | Binary Search Trees | Problem | Easy | Solution |
| 23 | BST Level-Order Traversal | Problem | Easy | Solution |
| 24 | More Linked Lists | Problem | Easy | Solution |
| 25 | Running Time and Complexity | Problem | Medium | Solution |
| 26 | Nested Logic | Problem | Easy | Solution |
| 27 | Testing | Problem | Easy | Solution |
| 28 | RegEx, Patterns, and Intro to Databases | Problem | Medium | Solution |
| 29 | Bitwise AND | Problem | Medium | Solution |
| Week | Challenge | Problem | Solution |
|---|---|---|---|
| One | Plus Minus | Problem | Solution |
| One | Mini-Max Sum | Problem | Solution |
| One | Time Conversion | Problem | Solution |
| One | Sparse Arrays | Problem | Solution |
| One | Lonely Integer | Problem | Solution |
| One | Flipping bits | Problem | Solution |
| One | Diagonal Difference | Problem | Solution |
| One | Counting Sort 1 | Problem | Solution |
| One | Pangrams | Problem | Solution |
| One | Permuting Two Arrays | Problem | Solution |
| One | Subarray Division 1 | Problem | Solution |
| One | XOR Strings 2 | Problem | Solution |
| Two | Sales by Match | Problem | Solution |
| Two | Zig Zag Sequence | Problem | Solution |
| Two | Drawing Book | Problem | Solution |
| Two | Tower Breakers | Problem | Solution |
| Two | Caesar Cipher | Problem | Solution |
| Two | Max Min | Problem | Solution |
| Two | Dynamic Array | Problem | Solution |
| Two | Grid Challenge | Problem | Solution |
| Two | Prime Dates | Problem | Solution |
| Two | Sherlock and Array | Problem | Solution |
| Two | Recursive Digit Sum | Problem | Solution |
| Two | Counter game | Problem | Solution |
| Two | Sum vs XOR | Problem | Solution |
| Three | The Bomberman Game | Problem | Solution |
| Three | New Year Chaos | Problem | Solution |
| Three | Sherlock and the Valid String | Problem | Solution |
| Three | Climbing the Leaderboard | Problem | Solution |
| Three | Reverse a linked list | Problem | Solution |
| Three | Reverse a doubly linked list | Problem | Solution |
| Three | Insert a node at a specific position in a linked list | Problem | Solution |
| Three | Merge two sorted linked lists | Problem | Solution |
| Three | Ice Cream Parlor | Problem | Solution |
| Three | Queue using Two Stacks | Problem | Solution |
| Three | Balanced Brackets | Problem | Solution |
| Three | Waiter | Problem | Solution |
| Three | Simple Text Editor | Problem | Solution |
| Four | Equal Stacks | Problem | Solution |
| Four | The Maximum Subarray | Problem | Solution |
| Four | Lego Blocks | Problem | Solution |
| Four | QHEAP1 | Problem | Solution |
| Four | Jesse and Cookies | Problem | Solution |
| Four | Hackerland Radio Transmitters | Problem | Solution |
| Four | Queries with Fixed Length | Problem | Solution |
| Four | Array Manipulation | Problem | Solution |
| Four | Highest Value Palindrome | Problem | Solution |
| Four | Lily's Homework | Problem | Solution |
| Four | Tree: Preorder Traversal | Problem | Solution |
| Four | Tree: Huffman Decoding | Problem | Solution |
| Four | Binary Search Tree : Lowest Common Ancestor | Problem | Solution |
| Four | No Prefix Set | Problem | Solution |
| Four | Castle on the Grid | Problem | Solution |
| Four | Roads and Libraries | Problem | Solution |
| Skill | Test | Difficulty | Description | Certificate |
|---|---|---|---|---|
| Problem Solving | Test | Basic | Data Structures (such as Arrays, Strings) and Algorithms (such as Sorting and Searching) | Certificate |
| Problem Solving | Test | Intermediate | Retrieving data from an API and process using parameters or paging | Certificate |
| Java | Test | Basic | Classes, Data Structures, Inheritance, Exception Handling, among others | Certificate |
| Python | Test | Basic | Scalar Types, Operators and Control Flow, Strings, Collections and Iteration, Modularity, Objects and Types and Classes | Certificate |
| JavaScript | Test | Basic | Functions, Currying, Hoisting, Scope, Inheritance, Events and Error Handling | Certificate |
| JavaScript | Test | Intermediate | It covers topics like Design Patterns, Memory management, concurrency model, and event loops, among others | Certificate |
| C# | Test | Basic | Data Types, and Variables, OOP, Properties and Indexers, Collections, Exception handling, among others | Certificate |
| SQL | Test | Basic | Queries, Relationships, and Aggregators | Certificate |