nikoo28 / java-solutions

Solutions in JAVA for some coding platforms.

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• How to use this repo
  • Install softwares
  • Setup Project
• CONTRIBUTE
• Solutions for some coding platforms
• Full list of questions
• Code Explanations
  • String
  • Array
  • Linked Lists
  • Trees
• Theory
  • Algorithmic Paradigms
  • Analysis of Algorithms
  • Sorting Techniques
  • Searching Techniques
  • Data Structures
• Playlists

How to use this repo

Install softwares

• Install OpenJDK
• Install Maven
• Install Git
• Use your favorite editor. (I prefer IntelliJ. It is fast and free)

Setup Project

• Goto your desired folder and clone the repository
• cd into your directory
• Build the project using mvn clean install.
• Startup IntelliJ and choose to import this project from your Explorer/Finder window.
• Start making changes/using it.

[user@machine ~] git clone https://github.com/nikoo28/java-solutions.git
[user@machine ~] cd java-solutions
[user@machine ~/java-solutions] mvn clean install
[INFO] Scanning for projects...
[INFO] 
[INFO] ----------< com.studyalgorithms.javasolutions:java-solutions >----------
[INFO] Building java-solutions 1.0-SNAPSHOT
[INFO] --------------------------------[ jar ]---------------------------------

... snipped

[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  7.790 s
[INFO] Finished at: 2020-07-06T18:37:35-07:00
[INFO] ------------------------------------------------------------------------
[user@machine ~/java-solutions]

Contribute

Please contribute to this repository to help it make better. Any change like new questions you want to see, code improvements, doc improvements etc. is very welcome. Just send me a pull request and I will review the request and approve it, if it looks good.

Solutions for some coding platforms

• LeetCode
• HackerRank
• Codility

Full list of questions

https://studyalgorithms.com/site-map/

Code Explanations

String

• Longest palindromic substring
• First unique character in a string
• Valid anagram strings
• HackerRank: Two Characters
• HackerRank: Two Strings
• HackerRank: Sherlock and the valid string
• LeetCode (#49): Group Anagrams

Array

• Single non-repeating number
• Maximum sum contiguous sub-array
• HackerRank: Left Rotation
• HackerRank: Equal Stacks
• HackerRank: Missing Numbers
• HackerRank: Pairs
• HackerRank: Between Two Sets
• HackerRank: Queue Using Two Stacks
• LeetCode (#1): Two Sum
• LeetCode (#33): Search in a Rotated Sorted Array
• HackerRank: Birthday Cake Candles
• LeetCode (#442): Find all Duplicates in an Array

Linked Lists

• Merge two sorted Linked Lists

Trees

• Diameter of a Binary Tree

Theory

Algorithmic Paradigms

• Algorithmic Paradigms: Brute Force
• Algorithmic Paradigms: Divide and Conquer
• Algorithmic Paradigms: Greedy
• Algorithmic Paradigms: Dynamic Programming
• Algorithmic Paradigms: Recursion

Analysis of Algorithms

• What is the Time Complexity of an Algorithm?
• How do you compare 2 Algorithms?
• What is the Big O notation?
• What is the Rate of Growth of an Algorithm?

Sorting Techniques

• Insertion Sort
• Bubble Sort
• Selection Sort
• Merge Sort
• Quick Sort
• Counting Sort
• Bucket Sort
• Radix Sort

Searching Techniques

• Linear Search
• Binary Search

Data Structures

• Arrays
• Stacks
• Queue
• Linked Lists
• Basic Operations on a Linked List

Playlists

• Secrets of Algorithmic Paradigms
• Analysis of Algorithms

java-solutions's Issues

FindTheDuplicateNumber

Hi Nikhil,
Thank you very much for the amazing videos on youtube and code in GitHub! It helps a lot to learn and solve algorithms. I need clarification on the solution provided for FindTheDuplicateNumber.java

If we try to access the index based on the values, wouldn't it throw the ArrayIndexOutOfBounds exception when the number is large? For example, the size of the input { 101, 324, 122, 15, 46, 39, 324, 131, 41, 324} is 9 but the values are much larger.

I don't know if there is an assumption where the values are within index.

Odd Even Linked List

Question

your answer

I can't understand about how the head returns the value.

Here, odd variable's value is assigned as head. But , how the head returns the answer ?

For example :

I assigned the value of "a" as 3 and "b" as "a". If I change the value of b. the value of "b" only changes .

But , how you returned the head as answer ?3

could you please answer me ?

add problems of recursion and dynamic programming

please try to add problems such as recursion which is back born of data structure and algorithm

Not accepted in leetCode

According to leet code, the following test case does not pass with the following question

[[1,1,0,0,1,0,0,1,1,0],[1,0,0,1,0,1,1,1,1,1],[1,1,1,0,0,1,1,1,1,0],[0,1,1,1,0,1,1,1,1,1],[0,0,1,1,1,1,1,1,1,0],[1,1,1,1,1,1,0,1,1,1],[0,1,1,1,1,1,1,0,0,1],[1,1,1,1,1,0,0,1,1,1],[0,1,0,1,1,0,1,1,1,1],[1,1,1,0,1,0,1,1,1,1]]

the required output should be:

[[2,1,0,0,1,0,0,1,1,0],[1,0,0,1,0,1,1,2,2,1],[1,1,1,0,0,1,2,2,1,0],[0,1,2,1,0,1,2,3,2,1],[0,0,1,2,1,2,1,2,1,0],[1,1,2,3,2,1,0,1,1,1],[0,1,2,3,2,1,1,0,0,1],[1,2,1,2,1,0,0,1,1,2],[0,1,0,1,1,0,1,2,2,3],[1,2,1,0,1,0,1,2,3,4]]

but our output is :

[[-2147483647,-2147483648,0,0,1,0,0,-2147483634,-2147483633,0],[-2147483648,0,0,1,0,-2147483637,-2147483636,-2147483635,-2147483634,1],[-2147483647,-2147483646,-2147483645,0,0,-2147483638,-2147483637,-2147483636,-2147483635,0],[0,-2147483645,-2147483644,-2147483643,0,-2147483639,-2147483638,-2147483637,-2147483636,1],[0,0,-2147483643,-2147483642,-2147483641,-2147483640,-2147483639,-2147483638,-2147483637,0],[-2147483640,-2147483641,-2147483642,-2147483641,-2147483640,-2147483639,0,-2147483637,-2147483636,-2147483635],[0,-2147483640,-2147483641,-2147483640,-2147483639,-2147483638,-2147483637,0,0,-2147483634],[-2147483638,-2147483639,-2147483640,-2147483639,-2147483638,0,0,-2147483631,-2147483632,-2147483633],[0,1,0,-2147483638,-2147483637,0,-2147483629,-2147483630,-2147483631,-2147483632],[1,2,1,0,-2147483636,0,-2147483628,-2147483629,-2147483630,-2147483631]]