Hackerrank

Solutions of Hackerrank challenges in various languages.

• Project Euler+
• Practice
  • Algorithms
  • Data Structures
  • Mathematics
  • Java
  • Functional Programming
  • Linux shell
  • SQL
  • Regex

Project Euler+

• Project Euler #1: Multiples of 3 and 5
• Project Euler #2: Even Fibonacci numbers
• Project Euler #3: Largest prime factor
• Project Euler #4: Largest palindrome product
• Project Euler #5: Smallest multiple
• Project Euler #6: Sum square difference
• Project Euler #7: 10001st prime
• Project Euler #8: Largest product in a series
• Project Euler #9: Special Pythagorean triplet
• Project Euler #10: Summation of primes
• Project Euler #11: Largest product in a grid
• Project Euler #12: Highly divisible triangular number
• Project Euler #13: Large sum
• Project Euler #14: Longest Collatz sequence
• Project Euler #15: Lattice paths
• Project Euler #16: Power digit sum
• Project Euler #17: Number to Words
• Project Euler #18: Maximum path sum I
• Project Euler #19: Counting Sundays
• Project Euler #20: Factorial digit sum
• Project Euler #22: Names scores
• Project Euler #36: Double-base palindromes
• Project Euler #67: Maximum path sum II

Algorithms

Warmup

• [Easy] Solve me first (1 pt)
• [Easy] Simple Array Sum (10 pts)
• [Easy] Staircase (10 pts)
• [Easy] Diagonal Difference (10 pts)
• [Easy] A Very Big Sum (10 pts)
• [Easy] Plus Minus (10 pts)
• [Easy] Time Conversion (15 pts)
• [Easy] Compare The Triples (10 pts)
• [Easy] Circular Array Rotation (20 pts)
• [Easy] Birthday Cake Candles (10 pts)

Implementation

• [Easy] Divisible Sum Pairs (10 pts)
• [Easy] Sequence Equation (20 pts)
• [Easy] Lisa's Workbook (30 pts)
• [Easy] Library Fine (15 pts)
• [Easy] Caesar Cipher (15 pts)
• [Easy] Angry Professor (20 pts)
• [Medium] Extra long factorials (20 pts)
• [Easy] Service Lane (20 pts)
• [Easy] Utopian Tree (20 pts)
• [Easy] Chocolate Feast (25 pts)
• [Easy] Modified Kaprekar Numbers (30 pts)
• [Easy] Sherlock and Squares (20 pts)
• [Easy] Manasa and Stones (30 pts)
• [Easy] Cut the sticks (25 pts)
• [Easy] Find Digits (25 pts)
• [Easy] Cavity Map (30 pts)
• [Easy] Sherlock and The Beast (30 pts)
• [Medium] Encryption (30 pts)
• [Easy] Strange Counter (30 pts)
• [Easy] Beautiful Triplets (20 pts)
• [Easy] Kangaroo (10 pts)
• [Easy] Save the Prisoner! (15 pts)
• [Easy] Minumum Distances (20 pts)
• [Easy] Jumping on the Clouds (20 pts)
• [Easy] Jumping on the Clouds: Revisited (15 pts)
• [Easy] Sock Merchant (10 pts)
• [Easy] Repeated String (20 pts)
• [Easy] Equalize the Array (20 pts)
• [Easy] Viral Advertising (15 pts)
• [Easy] Apple and Orange (10 pts)
• [Easy] Mini-Max Sum (10 pts)
• [Easy] Bon Appétit (10 pts)
• [Easy] Beautiful Days at the Movies (15 pts)
• [Easy] Designer PDF Viewer (20 pts)
• [Easy] Flatland Space Stations (25 pts)
• [Easy] Grading Students (10 pts)
• [Easy] Between Two Sets (10 pts)
• [Easy] The Hurdle Race (15 pts)
• [Easy] Taum and B'day (25 pts)
• [Easy] ACM ICPC Team (25 pts)
• [Easy] Drawing Book (10 pts)
• [Easy] Day of the Programmer (15 pts)
• [Easy] Electronics Shop (15 pts)
• [Easy] Migratory Birds (10 pts)
• [Easy] Picking Numbers (20 pts)
• [Easy] Birthday Chocolate (10 pts)
• [Easy] Breaking the Records (10 pts)
• [Easy] Cats and a Mouse (15 pts)
• [Easy] Counting Valleys (15 pts)

Strings

• [Easy] Super Reduced String (10 pts)
• [Easy] CamelCase (15 pts)
• [Easy] The Love-Letter Mystery (20 pts)
• [Easy] Alternating Characters (20 pts)
• [Easy] Gemstones (20 pts)
• [Easy] Pangrams (20 pts)
• [Easy] Game of Thrones - I (30 pts)
• [Easy] Funny String (25 pts)
• [Easy] Anagram (25 pts)
• [Easy] Beautiful Binary String (20 pts)
• [Easy] Mars Exploration (15 pts)
• [Easy] String Construction (25 pts)
• [Easy] Weighted Uniform Strings (25 pts)
• [Easy] Two Characters (20 pts)
• [Easy] Separate the Numbers (20 pts)
• [Easy] Making Anagrams (30 pts)
• [Medium] Sherlock and Anagrams (50 pts)
• [Difficult] Common Child (60 pts)

Sorting

• [Easy] Intro to Tutorial Challenges (30 pts)
• [Easy] Insertion Sort - Part 1 (30 pts)
• [Easy] Insertion Sort - Part 2 (30 pts)
• [Easy] Counting Sort 1 (30 pts)
• [Easy] Closest Numbers (35 pts)

Search

• [Easy] Ice Cream Parlor (30 pts)
• [Medium] Missing Numbers (45 pts)
• [Medium] Pairs (40 pts)

Graph Theory

• [Medium] Even Tree (50 pts)
• [Medium] Snakes and Ladders: The Quickest Way Up (50 pts)

Greedy

• [Medium] Flowers (35 pts)
• [Medium] Max Min (35 pts)
• [Easy] Two Arrays (40 pts)
• [Easy] Priyanka and Toys (30 pts)
• [Easy] Mark and Toys (35 pts)

Dynamic Programming

• [Easy] The Maximum Subarray (50 pts)

Bit Manipulation

• [Easy] Lonely Integer (20 pts)
• [Easy] Maximizing XOR (30 pts)
• [Easy] Flipping Bits (40 pts)
• [Easy] Sum vs XOR (25 pts)

Data Structures

Arrays

• [Easy] Arrays- DS (10 pts)

Linked Lists

• [Easy] Print the Elements of a linked list (5 pts)

Mathematics

Fundamentals

• [Easy] Find Point (5 pts)
• [Easy] Minimum Draws (5 pts)
• [Easy] Connecting Towns (10 pts)
• [Easy] Handshake (10 pts)
• [Easy] Halloween Party (20 pts)
• [Easy] Filling Jars (20 pts)
• [Medium] Is Fibo (20 pts)

Number Theory

• [Medium] Equations (60 pts)

Combinatorics

• [Expert] Building a List (40 pts)
• [Easy] Picking Cards (50 pts)
• [Medium] Consecutive Subsequences (50 pts)

Probability

• [Easy] B'day Gift (30 pts)

Java

Introduction

• [Easy] Welcome To Java! (3 pts)
• [Easy] Java If-Else (10 pts)
• [Easy] Java Stdin and Stdout 1 (5 pts)
• [Easy] Java Stdin and Stdout 2 (10 pts)
• [Easy] Java Output Formatting (10 pts)
• [Easy] Java Loops I (10 pts)
• [Easy] Java Loops II (10 pts)
• [Easy] Java Datatypes (10 pts)
• [Easy] Java End-of-file (10 pts)
• [Easy] Java Static Initializer Block (10 pts)
• [Easy] Java Int to String (10 pts)
• [Easy] Java Date and Time (15 pts)
• [Easy] Java Currency Formatter (15 pts)

Strings

• [Easy] Java Strings Introduction (5 pts)

SQL

Basic Select

• [Easy] Select All (10 pts)
• [Easy] Revising the Select Query - 1 (10 pts)
• [Easy] Revising the Select Query - 2 (10 pts)
• [Easy] Select by ID (10 pts)
• [Easy] Japanese Cities' Detail (10 pts)
• [Easy] Japanese Cities' Names (10 pts)
• [Easy] Weather Observation Station 1 (15 pts)
• [Easy] Weather Observation Station 3 (10 pts)
• [Easy] Weather Observation Station 4 (10 pts)
• [Medium] Weather Observation Station 5 (30 pts)
• [Easy] Weather Observation Station 6 (10 pts)
• [Easy] Weather Observation Station 7 (10 pts)
• [Easy] Weather Observation Station 8 (15 pts)
• [Easy] Weather Observation Station 9 (10 pts)
• [Easy] Weather Observation Station 10 (10 pts)
• [Easy] Weather Observation Station 11 (15 pts)
• [Easy] Weather Observation Station 12 (15 pts)
• [Medium] Higher Than 75 Marks (15 pts)

Linux Shell

Bash

• [Easy] Let's Echo (1 pt)
• [Easy] Looping and Skipping (2 pts)
• [Easy] A Personalized Echo (1 pt)
• [Easy] Looping with Numbers (2 pts)
• [Easy] The World of Numbers (2 pts)
• [Easy] Comparing Numbers (3 pts)
• [Easy] Getting started with conditionals (3 pts)

Text Processing

• [Easy] Cut #1 (1 pt)
• [Easy] Cut #2 (1 pt)
• [Easy] Head of a Text File #1 (2 pts)
• [Easy] Head of a Text File #2 (2 pts)
• [Easy] Tr' Command #1 (1 pt)
• [Easy] Sort Command #1 (1 pt)
• [Easy] Sort Command #2 (1 pt)
• [Easy] Tr' Command #2 (1 pt)

Grep Sed Awk

• [Easy] Grep' #1 (2 pts)
• [Easy] Grep' #2 (2 pts)

Functional Programming

Introduction

• [Easy] Solve me first FP (3 pts)
• [Easy] Lambda Calculus - Evaluating Expressions #1 (5 pts)
• [Easy] Lambda Calculus - Evaluating Expressions #2 (5 pts)
• [Easy] Lambda Calculus - Evaluating Expressions #3 (5 pts)
• [Medium] Lambda Calculus - Evaluating Expressions #4 (5 pts)
• [Medium] Lambda Calculus - Evaluating Expressions #5 (5 pts)
• [Easy] Lambda Calculus - Reductions #1 (5 pts)
• [Easy] Lambda Calculus - Reductions #2 (5 pts)
• [Medium] Lambda Calculus - Reductions #3 (5 pts)
• [Medium] Lambda Calculus - Reductions #4 (5 pts)
• [Easy] Hello World (5 pts)
• [Easy] Hello World N Times (5 pts)
• [Easy] List Replication (10 pts)
• [Easy] Filter Array (10 pts)
• [Easy] Update List (10 pts)
• [Easy] List Length (10 pts)
• [Easy] Array Of N Elements (10 pts)
• [Easy] Reverse a list (10 pts)
• [Easy] Sum of odd elements (10 pts)
• [Easy] Filter positions in a list (10 pts)
• [Easy] Evaluating e^x (20 pts)
• [Easy] Area Under Curves and Volume of Revolving a Curve (30 pts)
• [Easy] Functions or Not (5 pts)
• [Easy] Compute the Perimeter of a Polygon (15 pts)
• [Easy] Compute the Area of a Polygon (20 pts)

Recursion

• [Easy] Computing the GCD (2 pts)
• [Easy] Fibonacci Numbers (2 pts)
• [Easy] Pascal's Triangle (10 pts)
• [Easy] String Mingling (20 pts)
• [Easy] String-o-Permute (10 pts)
• [Easy] String Reductions (10 pts)
• [Easy] Prefix Compression (10 pts)
• [Easy] Sequence full of colors (10 pts)
• [Easy] String Compression (10 pts)
• [Medium] Super Digit (20 pts)

Ad Hoc

• [Easy] Remove Duplicates (10 pts)
• [Easy] Rotate String (20 pts)
• [Easy] Jumping Bunnies (20 pts)
• [Easy] Missing Numbers (FP) (30 pts)

Regex

Introduction

• [Easy] Matching Specific String (5 pts)
• [Easy] Matching Word & Non-Word Character (5 pts)
• [Easy] Matching Digits & Non-Digit Characters (5 pts)
• [Easy] Matching Whitespace & Non-Whitespace Character (5 pts)
• [Easy] Matching Anything But a Newline (5 pts)
• [Easy] Matching Start & End (5 pts)

Character Class

• [Easy] Matching Specific Characters (10 pts)
• [Easy] Excluding Specific Characters (10 pts)
• [Easy] Matching Range Of Characters (10 pts)

Repetitions

• [Easy] Matching {x} Repetitions (20 pts)
• [Easy] Matching {x,y} Repetitions (20 pts)
• [Easy] Matching Zero Or More Repetitions (20 pts)
• [Easy] Matching One Or More Repetitions (20 pts)
• [Easy] Matching Ending Items (20 pts)

Grouping and Capturing

• [Easy] Matching Word Boundaries (20 pts)
• [Easy] Capturing & Non-Capturing Groups (20 pts)
• [Easy] Alternative Matching (20 pts)

Applications

• [Easy] HackerRank Tweets (5 pts)
• [Easy] Split the Phone Numbers (5 pts)
• [Easy] Find Hackerrank (5 pts)
• [Easy] The British and American Style of Spelling (5 pts)
• [Easy] Find a Substring (5 pts)
• [Easy] Alien Username (5 pts)
• [Easy] Detecting Valid Latitude and Longitude Pairs (20 pts)
• [Easy] Valid PAN Format (5 pts)
• [Easy] IP Address Validation (10 pts)
• [Easy] Detect HTML Attributes (10 pts)
• [Easy] Detect HTML Tags (10 pts)