sudheerj / datastructures-algorithms

List of Programs related to data structures and algorithms

datastructures-algorithms

List of Programs related to data structures and algorithms

Data Structures

Stack

No.	Name	Source	Live	Documentation	Level	Pattern
1	Stack using array	Source	JavaScript	-	Easy	Using Array operations
2	Stack using linkedlist	Source	JavaScript	-	Easy	Using LinkedList operations

Queue

1. Queue using array: JavaScript
2. Queue using linkedlist: JavaScript

SinglyLinkedlist

1. SinglyLinkedlist implementation: Source Playground Documentation

DoublyLinkedlist

1. DoublyLinkedlist implementation: Source Playground Documentation

Tree

1. Binary Search Tree: Source JavaScript Documentation

Graphs

1. Unweighted undirected graph: Source Playground Documentation

HashTable

1. HashTable: JavaScript

Algorithms

Array

No.	Name	Source	Live	Documentation	Level	Pattern
1	Contains duplicates	Source	Playground	Documentation	Easy	Set/Object
2	Two sum2- Input array sorted	Source	Playground	Documentation	Medium	Two pointers
3	3 sum	Source	Playground	Documentation	Medium	Two pointers
4	Product of array except self	Source	Playground	Documentation	Medium	Prefix and postfix pattern
5	Max sum subarray	Source	Playground	Documentation	Medium	Kadane's algorithm
6	Minimum size subarray sum	Source	Playground	Documentation	Medium	Sliding window
7	Sort Colors	Source	Playground	Documentation	Medium	Two pointers
8	Maximum product subarray	Source	Playground	Documentation	Medium	Kadane's algorithm
9	Find minimum in rotated sorted array	Source	Playground	Documentation	Medium	Binary search technique
10	Maximum Circular subarray	Source	Playground	Documentation	Medium	Kadane's algorithm
11	Rotate array	Source	Playground	Documentation	Medium	Two pointers
12	Search in rotated sorted array	Source	Playground	Documentation	Medium	Binary search
13	Container with most water	Source	Playground	Documentation	Medium	Two pointers
14	First missing positive number	Source	JavaScript	Documentation	Hard	In-place hashing
15	Best time to buy stock and sell stock	Source	JavaScript	Documentation	Easy	Greedy algorithm
16	Two missing numbers	Source	JavaScript	Documentation	Medium	Sum and average calculations
17	Pascal's Triangle	Source	JavaScript	Documentation	Easy	Array traversal and sequential sum
18	Remove Element	Source	JavaScript	Documentation	Easy	Array traversal
19	Can place flowers	Source	JavaScript	Documentation	Easy	Array traversal and comparison
20	Majority Element	Source	JavaScript	Documentation	Easy	Boyer Moore Voting algorithm
21	Pivot Index	Source	JavaScript	Documentation	Easy	Array traversal
22	Range Sum queries	Source	JavaScript	Documentation	Easy	Array traversal
23	Disappeared numbers	Source	JavaScript	Documentation	Easy	Array traversal
24	Identical pairs	Source	JavaScript	Documentation	Easy	Array traversal & map
25	Destination City	Source	JavaScript	Documentation	Easy	Array traversal & set
26	Set mismatch	Source	JavaScript	Documentation	Easy	Array traversal & marking numbers
27	Intersection of arrays	Source	JavaScript	Documentation	Easy	Set and array traversal
29	Special array	Source	JavaScript	Documentation	Easy	Frequency counter and array traversal

String

No.	Name	Source	Live	Documentation	Level	Pattern
1	Longest substring without repeating characters	Source	JavaScript	Documentation	Medium	Sliding Window
2	Longest repeating character replacement	Source	JavaScript	Documentation	Medium	Sliding Window
3	Minimum window substring	Source	JavaScript	Documentation	Hard	Sliding Window
4	Valid anagram	Source	JavaScript	Documentation	Easy	Frequency counting
5	Group anagrams	Source	JavaScript	Documentation	Medium	Frequency counting
6	Valid palindrome	Source	JavaScript	Documentation	Easy	Two pointer
7	Longest palindromic substring	Source	JavaScript	Documentation	Medium	Expanding around center
8	Palindromic substrings	Source	JavaScript	Documentation	Medium	Expanding around center
9	Encode and decode strings	Source	JavaScript	Documentation	Medium	Basic string and array operations
10	Greatest common devisor of strings	Source	JavaScript	Documentation	Easy	Euclidean and String operations
11	Reverse words in string	Source	JavaScript	Documentation	Medium	Basic string and array operations
12	Length of last word	Source	JavaScript	Documentation	Easy	String traversal

Dynamic programming

No.	Name	Source	Live	Documentation	Level	Pattern
1	Climbing stairs	Source	JavaScript	Documentation	Medium	Dynamic programming
2	Coin change	Source	JavaScript	Documentation	Medium	Dynamic programming
3	Longest increasing subsequence	Source	JavaScript	Documentation	Medium	Dynamic programming(Bottom up)
4	Longest common subsequence	Source	JavaScript	Documentation	Medium	Two-dimentional bottom up Dynamic programming
5	Word break	Source	JavaScript	Source	Medium	Bottom up dynamic programming
6	Combination Sum 4	Source	JavaScript	Documentation	Medium	Bottom up Dynamic programming
7	House robber	Source	JavaScript	Documentation	Medium	Fibonacci pattern bottom-up dynamic programming
8	House robber 2	Source	JavaScript	Documentation	Medium	Bottom-up dynamic programming
9	Decode ways	Source	JavaScript	Documentation	Medium	Dynamic programming
10	Unique paths	Source	JavaScript	Documentation	Medium	Dynamic programming
11	Jump game	Source	JavaScript	Documentation	Medium	Dynamic programming or Greedy

Binary

No.	Name	Source	Playground	Documentation	Level	Pattern
1	Sum of two integers	Source	JavaScript	Documentation	Medium	Bitwise operations
2	Number of 1 Bits	Source	JavaScript	Documentation	Easy	Brian Kernighans
3	Counting Bits	Source	JavaScript	Documentation	Easy	Dynamic programming
4	Missing number	Source	JavaScript	Documentation	Easy	Bitwise XOR
5	Reverse Bits	Source	JavaScript	Documentation	Easy	Bitwise operations

Stack

No.	Name	Source	Playground	Documentation	Level	Pattern
1	Sort Stack	Source	JavaScript	Documentation	Easy	Stack push & pop
2	Balanced Brackets	Source	JavaScript	Documentation	Medium	Stack push and pop
3	Reverse Polish Notation	Source	JavaScript	Documentation	Medium	Stack push & pop
4	Daily Temperatures	Source	JavaScript	Documentation	Medium	Monotonic decreasing stack
5	Number of People See In Queue	Source	JavaScript	Documentation	Medium	Monotonic decreasing stack

LinkedList

No.	Name	Source	Playground	Documentation	Level	Pattern
1	Reverse sublist	Source	JavaScript	Documentation	Easy	List traversal
2	Detect cycle in a linkedlist	Source	Playground	Documentation	Easy	Floyd's cycle-finding or Tortoise and Hare algorithm
3	Merge two sorted lists	Source	JavaScript	Documentation	Easy	Arithmetic comparison
4	Merge K sorted lists	Source	JavaScript	Documentation	Hard	Divide and conquer
5	Remove Kth node from end of list	Source	JavaScript	Documentation	Medium	Two pointers
6	Reorder list	Source	Javascript	Documentation	Medium	Two pointers
7	Find middle node	Source	JavaScript	Documentation	Easy	Two pointers
8	Find Kth node from end of list	Source	JavaScript	Documentation	Easy	Two pointers
9	Partition list	Source	JavaScript	Documentation	Medium	Two pointers
10	Remove duplicates	Source	JavaScript	Documentation	Easy	Two pointers
11	Binary to decimal	Source	JavaScript	Documentation	Easy	List traversal and math operations

Doubly linkedlist

No.	Name	Source	Playground	Documentation	Level	Pattern
1	Swap first and last	Source	JavaScript	Documentation	Easy	Swap nodes
2	Palindrome check	Source	Playground	Documentation	Easy	Two pointers
3	Swap node pairs	Source	JavaScript	Documentation	Medium	List traversal and update pointers

Tree

No.	Name	Source	Playground	Documentation	Level	Pattern
1	Maximum depth of binary tree	Source	JavaScript	Documentation	Easy	Depth First Search(DFS) with recursion
2	Same tree	Source	JavaScript	Documentation	Easy	Depth First Search(DFS) with recursion
3	Invert or Flip binary tree	Source	JavaScript	Documentation	Easy	Swapping nodes and Depth First Search(DFS) with recursion
4	Binary tree maximum path sum	Source	JavaScript	Documentation	Hard	DFS using recursion
5	Binary tree level order traversal	Source	JavaScript	Documentation	Easy	Depth First Search(DFS) with recursion
6	Serialize and deserialize binary tree	Source	JavaScript	Documentation	Hard	DFS preorder traversal
7	Subtree of another tree	Source	JavaScript	Documentation	Easy	Depth First Search(DFS) with recursion
8	Construct binary tree from preorder and inorder traversal	Source	JavaScript	Documentation	Medium	DFS with recursion
9	Validate BST	Source	JavaScript	Documentation	Medium	Depth-First-Search(DFS) using recursion
10	Kth smallest element in BST	Source	JavaScript	Documentation	Medium	Iterative inorder traversal using stack
11	Lowest Common Ancestor of BST	Source	JavaScript	Documentation	Medium	Iterative tree traversal
12	Trie	Source	JavaScript	Documentation	Medium	Iteration over string characters
13	Design and Search words Datastructure	Source	JavaScript	Documentation	Medium	Trie and DFS recursion
14	Word search 2	Source	JavaScript	Documentation	Hard	Backtracking with Trie

Graph

No.	Name	Source	Live	Documentation	Level	Pattern
1	Clone graph	Source	JavaScript	Documentation	Medium	Depth-First-Search(DFS) using recursion
2	Course schedule	Source	JavaScript	Documentation	Medium	DFS using recursion
3	Pacific Atlantic waterflow	Source	Playground	Documentation	Medium	DFS using recursion
4	Number of Islands	Source	JavaScript	Documentation	Medium	DFS using recursion
5	Alien dictionary	Source	JavaScript	Documentation	Hard	Kahn's algorithm for topological sorting
6	Graph valid tree	Source	JavaScript	Documentation	Medium	Union Find algorithm(+ union by rank & path compression)
7	Number of connected components in an undirected graph	Source	JavaScript	Documentation	Medium	Union Find algorithm(+ union by rank & path compression)
8	Walls and gates	Source	JavaScript	Documentation	Medium	BFS traversal

Matrix

No.	Name	Source	Live	Documentation	Level	Pattern
1	Set matrix zeros	Source	JavaScript	Documentation	Medium	In-place updates through traversal
2.	Spiral matrix	Source	JavaScript	Documentation	Medium	Boundary matrix traversal/spiral pattern
3	Rotate image	Source	JavaScript	Documentation	Medium	Inplace square rotation
4	Word search	Source	JavaScript	Documentation	Medium	Depth-First Search (DFS) using recursion

Interval

No.	Name	Source	Live	Documentation	Level	Pattern
1	Insert interval	Source	JavaScript	Documentation	Medium	Basic math operations
2	Merge interval	Source	JavaScript	Documentation	Medium	Sorting and basic math operations
3	Non-overlapping intervals	Source	JavaScript	Documentation	Medium	Greedy and basic math operations
4	Meeting rooms	Source	JavaScript	Documentation	Medium	Greedy and basic math operations
5	Meeting rooms 2	Source	JavaScript	Documentation	Medium	Two pointers

Hashtable

No.	Name	Source	Live	Documentation	Level	Pattern
1	Duplicates	Source	JavaScript	JavaScript	Easy	Using Map
2	Two sum	Source	JavaScript	Documentation	Easy	Using Map
3	First non repeating character	Source	JavaScript	Documentation	Easy	Using Map
4	Group anagrams	Source	JavaScript	Documentation	Medium	Using Map & its methods
5	Verify Common Elements	Source	JavaScript	Documentation	Easy	Using Map methods
6	Longest consequtive sequence	Source	JavaScript	Documentation	Medium	Find sequence using set or hash table
7	Valid Sudoku	Source	JavaScript	Documentation	Medium	Using Map and Set methods
8	Letter combinations	Source	JavaScript	Documentation	Medium	Backtracking with hash table mapping
9	LRU Cache	Source	JavaScript	Documentation	Medium	Combination of Hash Table and doubly linked list
10	Maximum number of balloons	Source	JavaScript	Documentation	Easy	Hash map on characters
11	Isomorphic Strings	Source	JavaScript	Documentation	Easy	mapping characters using Hash maps
14	First unique character	Source	JavaScript	Documentation	Easy	Hashing for character count

Sorting

No.	Name	Source	Playground	Documentation	Level	Complexity
1	Bubble sort	Source	JavaScript	Documentation	Easy	TC: O(n2), SC: O(1)
2	Selection sort	Source	JavaScript	Documentation	Easy	TC: O(n2), SC: O(1)
3	Insertion sort	Source	JavaScript	Documentation	Easy	TC: O(n2), SC: O(1)
4	Merge sort	Source	JavaScript	Documentation	Medium	TC: O(n log(n)), SC: O(n)
5	Quick sort	Source	JavaScript	Documentation	Medium	TC: O(n2), SC: O(log n)
6	Heap sort	Source	JavaScript	Documentation	Hard	TC: O(n log(n)), SC: O(1)

datastructures-algorithms's Issues

"Two sum2- Input array sorted" typo for "right pointer" in step 5 of recommended solutions

Hi. in the "Two sum2- Input array sorted" problem, step 5 of the recommended algorithm link says that the "right" pointer should be decremented but in solution link, it implemented in such a way that "left" pointer is incremented. I think the recommended algorithm should be edited.

Typo in the README.md

Description

As l was reading through the README, l came across the typo "Strctures".

[bug] In longestPalindromicSubstring, right is not incremented or decremented

In the even length section, right is not incremented or decremented.

        left = i; right = i+1;
        while(left >=0 && right < str.length && str[left] === str[right]) {
            if(right-left+1 > longestSubstrLen) {
                longestSubstr = str.substring(left, right+1);
                longestSubstrLen = right-left+1;
            }
            left--;
            right;  

[bug] Binary Search Tree unreachable code

Problem is unnecessary returns after while loops.

    insert(value) {
        const newNode = new Node(value);
        if(this.root === null) {
            this.root = newNode;
            return this;
        } 
            let currentNode = this.root;
            while(true) {
                if(value < currentNode.value) {
                    // Left
                    if(currentNode.left ===  null) {
                        currentNode.left = newNode;
                        return this;
                    }
                    currentNode = currentNode.left
                } else if (value > currentNode.right){
                    // Right
                    if(currentNode.right === null) {
                        currentNode.right = newNode;
                        return this;
                    }
                    currentNode = currentNode.right;
                }  else {
                    return this;
                }
            }
        return this; // I think this is unreachable -> once inside the while loop, execution won't leave that code block
    }

I think this same mistake is repeated in the lookup function where you return false after another while loop.

Code Playgrounds

Great work. Thank you!

I suggest adding playgrounds to allow trying out code, similar to TheAlgorithms website, which uses LiveCodes (see example).

Please allow me to introduce LiveCodes, a feature-rich, open-source, client-side, code playground that supports 80+ languages and frameworks, including JS, TS, React, Vue, Svelte, Solid, Python, Go, Ruby, PHP and others (see starter templates). The announcement post gives a general overview.

Projects can be shared, exported and deployed (to GitHub Pages). Code can be imported from many sources including GitHub.

LiveCodes is very configurable. Many of the features can be configured by query parameters

For example, to load the bubble sort algorithm from this URL:

https://github.com/sudheerj/datastructures-algorithms/blob/master/src/javascript/algorithms/sorting/bubbleSortLinkedlist.js

Add it to the query parameter x like that, (also have the console open):

https://livecodes.io/?console=open&x=https://github.com/sudheerj/datastructures-algorithms/blob/master/src/javascript/algorithms/sorting/bubbleSortLinkedlist.js

open in LiveCodes

Screenshot:

You may want, for example, to add links to the algorithms in the repo README like that:

---

Bubble Sort: implementation - playground

---

LiveCodes also allows running automated tests (using Jest). This feature is used by TheAlgorithms website to validate the algorithms implementation.

Playgrounds can also be embedded in any webpage, using a powerful, yet easy-to-use, SDK.

Comprehensive documentations are available with live demos, code samples and screenshots.

LiveCodes is free with unlimited usage, no ads and no account required. It can be easily self-hosted (if you want), and can be used for commercial projects (MIT license).

Disclosure: obviously, I'm the author of LiveCodes.

If you feel this can be useful, I can help getting started with providing playgrounds for the code in this repo or for other projects.

I thought you would be interested. Otherwise, please feel free to close this.
Thank you.