Welcome to my comprehensive SDE Interview Prep repository! This repo is a one-stop hub that covers A-Z of Data Structures and Algorithms, System Design and CS Core crafted specifically for mastering technical interviews at product-based companies and high-growth startups.

Each problem is thoughtfully categorized, solved in C++, and accompanied by detailed Markdown explanations to help you understand the logic, intuition, and edge cases. Whether you're brushing up on fundamentals or tackling advanced topics — this repo's got you.

📌 DSA Sources: Striver's A2Z , NeetCode 150 , Blind 75 , Top Interview 150
📌 System Design Sources: System Design Primer

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📁 Data Structures and Algorithms

[ 📄 .md files for explanation | 💻 .cpp files for code implementation ]

🧠 Basics

Category	Problem / Algorithm	Explanation	Code
📘 1. Maths	Count the Digits	📄 MD	–
📘 1. Maths	Reverse a Number	📄 MD	–
📘 1. Maths	Palindrome Number	📄 MD	–
📘 1. Maths	GCD	📄 MD	–
📘 1. Maths	Armstrong Number	📄 MD	–
📘 1. Maths	All Divisors	📄 MD	–
📘 1. Maths	Check Prime	📄 MD	–
🔁 2. Recursion	Print N Names	📄 MD	💻 CPP
🔁 2. Recursion	1 to N	📄 MD	💻 CPP
🔁 2. Recursion	N to 1	📄 MD	💻 CPP
🔁 2. Recursion	Sum of N	📄 MD	💻 CPP
🔁 2. Recursion	Factorial of N	📄 MD	💻 CPP
🔁 2. Recursion	Reverse Array	📄 MD	💻 CPP
🔁 2. Recursion	Palindrome String	📄 MD	💻 CPP
🔁 2. Recursion	Fibonacci	📄 MD	💻 CPP
🔐 3. Hashing	Frequency of Array Elements	📄 MD	💻 CPP
🔐 3. Hashing	Highest & Lowest Freq Element	📄 MD	💻 CPP
🔐 3. Hashing	First Unique Character	📄 MD	💻 CPP
🔐 3. Hashing	Find Difference	📄 MD	💻 CPP
🔐 3. Hashing	Find Duplicates	📄 MD	💻 CPP
🔐 3. Hashing	Is Anagram	📄 MD	💻 CPP

🔢 Sorting

Category	Problem / Algorithm	Explanation	Code
📑 1. Elementary	Selection Sort	📄 MD	💻 CPP
📑 1. Elementary	Bubble Sort	📄 MD	💻 CPP
📑 1. Elementary	Insertion Sort	📄 MD	💻 CPP
📈 2. Advanced	Merge Sort	📄 MD	💻 CPP
📈 2. Advanced	Quick Sort	📄 MD	💻 CPP
📈 2. Advanced	Heap Sort	📄 MD	💻 CPP
📈 2. Advanced	Radix Sort	📄 MD	💻 CPP

♠️ Arrays

Category	Problem / Algorithm	Explanation	Code
📑 1. Easy	Largest Element in the Array	📄 MD	💻 CPP
📑 1. Easy	Second Largest Element in the Array	📄 MD	💻 CPP
📑 1. Easy	Is Array Sorted?	📄 MD	💻 CPP
📑 1. Easy	Remove Duplicates from Array	📄 MD	💻 CPP
📑 1. Easy	Left Rotate by One	📄 MD	💻 CPP
📑 1. Easy	Rotate Array by K Places	📄 MD	💻 CPP
📑 1. Easy	Shift Zeros to End	📄 MD	💻 CPP
📑 1. Easy	Linear Search	📄 MD	💻 CPP
📑 1. Easy	Find The Union	📄 MD	💻 CPP
📑 1. Easy	Find The Intersection	📄 MD	💻 CPP
📑 1. Easy	Find The Missing Number	📄 MD	💻 CPP
📑 1. Easy	Max Consecutive Ones	📄 MD	💻 CPP
📑 1. Easy	Number that Appears Once	📄 MD	💻 CPP
📑 1. Easy	Longest Subarray with Sum K	📄 MD	💻 CPP
📑 1. Easy	Remove K From Array	📄 MD	💻 CPP
📑 1. Easy	One Plus	📄 MD	💻 CPP
📑 1. Easy	Remove Value From Array	📄 MD	💻 CPP
📑 1. Easy	Container With Most Water	📄 MD	💻 CPP
📑 1. Easy	Move Zeros To End	📄 MD	💻 CPP
📃 2. Medium	Two Sum	📄 MD	💻 CPP
📃 2. Medium	Sort an Array of 0s, 1s & 2s	📄 MD	💻 CPP
📃 2. Medium	Majority Element - I [> n/2]	📄 MD	💻 CPP
📃 2. Medium	Maximum Sub-Array Sum	📄 MD	💻 CPP
📃 2. Medium	Best Time to Buy and Sell Stock	📄 MD	💻 CPP
📃 2. Medium	Rearrange Elements by Sign [Alternating]	📄 MD	💻 CPP
📃 2. Medium	Next Permutation	📄 MD	💻 CPP
📃 2. Medium	Leaders in an Array	📄 MD	💻 CPP
📃 2. Medium	Longest Consecutive Sequence	📄 MD	💻 CPP
📃 2. Medium	Set Matrix Zeros	📄 MD	💻 CPP
📃 2. Medium	Rotate Matrix By 90 Degrees	📄 MD	💻 CPP
📃 2. Medium	Matrix Spiral Traversal	📄 MD	💻 CPP
📃 2. Medium	Sub Arrays With Sum K	📄 MD	💻 CPP
📃 2. Medium	Partition Labels	📄 MD	💻 CPP
📃 2. Medium	Sorted Array Squares	📄 MD	💻 CPP
📃 2. Medium	Boats To Save People	📄 MD	💻 CPP
📃 2. Medium	Simple Bank System	📄 MD	💻 CPP
📃 2. Medium	Laser Beams in a Bank	📄 MD	💻 CPP
📃 2. Medium	Count Ungaurded Cells	📄 MD	💻 CPP
📜 2. Hard	Pascal's Triangle	📄 MD	💻 CPP
📜 2. Hard	Majority Element - II [> n/3]	📄 MD	💻 CPP
📜 2. Hard	Three Sum	📄 MD	💻 CPP
📜 2. Hard	Four Sum	📄 MD	💻 CPP
📜 2. Hard	Count Subarrays with Xor K	📄 MD	💻 CPP
📜 2. Hard	Merge Overlapping Intervals	📄 MD	💻 CPP
📜 2. Hard	Merge Sorted Arrays	📄 MD	💻 CPP
📜 2. Hard	Find Repeating and Missing Numbers	📄 MD	💻 CPP
📜 2. Hard	Count Inversions	📄 MD	💻 CPP
📜 2. Hard	Reverse Pairs	📄 MD	💻 CPP
📜 2. Hard	Maximum Product Subarray	📄 MD	💻 CPP
📜 2. Hard	Product of Array except Self	📄 MD	💻 CPP

🔍 Binary Search

Category	Problem / Algorithm	Explanation	Code
⁉️ 3. BS on 1D	Binary Search on Sorted Array	📄 MD	💻 CPP
⁉️ 3. BS on 1D	Search Insert Position	📄 MD	💻 CPP
⁉️ 3. BS on 1D	First and Last Occurance in a Sorted Array	📄 MD	💻 CPP
⁉️ 3. BS on 1D	Search in a Rotated Sorted Array - I	📄 MD	💻 CPP
⁉️ 3. BS on 1D	Search in a Rotated Sorted Array - II	📄 MD	💻 CPP
⁉️ 3. BS on 1D	Minimum in Rotated Sorted Array	📄 MD	💻 CPP
⁉️ 3. BS on 1D	Single Element in a Sorted Array	📄 MD	💻 CPP
⁉️ 3. BS on 1D	Find Peak Element - I	📄 MD	💻 CPP
⁉️ 3. BS on 1D	Arranging Coins	📄 MD	💻 CPP
⁉️ 3. BS on 1D	First Bad Version	📄 MD	💻 CPP
‼️ 2. BS on Answers	Koko Eating Bananas	📄 MD	💻 CPP
‼️ 2. BS on Answers	Days to make M Bouquets	📄 MD	💻 CPP
‼️ 2. BS on Answers	Smallest Divisor within the Threshold	📄 MD	💻 CPP
‼️ 2. BS on Answers	Capacity to Ship within D Days	📄 MD	💻 CPP
‼️ 2. BS on Answers	Find the K-th Missing Element	📄 MD	💻 CPP
‼️ 2. BS on Answers	Aggressive Cows	📄 MD	💻 CPP
‼️ 2. BS on Answers	Book Allocation	📄 MD	💻 CPP
‼️ 2. BS on Answers	Split Array to Largest Sum	📄 MD	💻 CPP
‼️ 2. BS on Answers	Minimize Max Distance between Gas Stations	📄 MD	💻 CPP
‼️ 2. BS on Answers	Median of Two Sorted Arrays	📄 MD	💻 CPP
‼️ 2. BS on Answers	Time Map	📄 MD	💻 CPP
⁉️ 3. BS on 2D	Row with Maximum 1s	📄 MD	💻 CPP
⁉️ 3. BS on 2D	Search in a 2D Matrix - I	📄 MD	💻 CPP
⁉️ 3. BS on 2D	Search in a 2D Matrix - II	📄 MD	💻 CPP
⁉️ 3. BS on 2D	Find Peak Element - II	📄 MD	💻 CPP

🧵 Strings

Category	Problem / Algorithm	Explanation	Code
🐕 Easy	Remove Outer Parenthesis	📄 MD	💻 CPP
🐕 Easy	Largest Odd Number	📄 MD	💻 CPP
🐕 Easy	Longest Common Prefix	📄 MD	💻 CPP
🐕 Easy	Isomorphic Strings	📄 MD	💻 CPP
🐕 Easy	Rotate String	📄 MD	💻 CPP
🐕 Easy	Is Anagram ?	📄 MD	💻 CPP
🐕 Easy	Valid Palindrome	📄 MD	💻 CPP
🐈 Medium	Frequency Sort	📄 MD	💻 CPP
🐈 Medium	Max Depth of Parenthesis	📄 MD	💻 CPP
🐈 Medium	Roman to Integer	📄 MD	💻 CPP
🐈 Medium	String to Integer (ATOI)	📄 MD	💻 CPP
🐈 Medium	Longest Palindrome Substrings	📄 MD	💻 CPP
🐈 Medium	Sum of Beauty of Substrings	📄 MD	💻 CPP
🐈 Medium	Reverse Words in a String	📄 MD	💻 CPP
🐈 Medium	Group Anagrams	📄 MD	💻 CPP
🐈 Medium	Longest Substring without Repeating Char	📄 MD	💻 CPP

🔗 Linked Lists

Category	Problem / Algorithm	Explanation	Code
➡️ Singly LL	Linked List Constructors	📄 MD	💻 CPP
➡️ Singly LL	Array to Linked List	📄 MD	💻 CPP
➡️ Singly LL	Insertion at Head	📄 MD	💻 CPP
➡️ Singly LL	Insertion at Tail	📄 MD	💻 CPP
➡️ Singly LL	Insertion at K	📄 MD	💻 CPP
➡️ Singly LL	Deletion from Head	📄 MD	💻 CPP
➡️ Singly LL	Deletion from Tail	📄 MD	💻 CPP
➡️ Singly LL	Deletion from K	📄 MD	💻 CPP
➡️ Singly LL	Length of Linked List	📄 MD	💻 CPP
➡️ Singly LL	Search K in Linked List	📄 MD	💻 CPP
🔀 Doubly LL	Array to DLL	📄 MD	💻 CPP
🔀 Doubly LL	Insertion at Head	📄 MD	💻 CPP
🔀 Doubly LL	Insertion at Tail	📄 MD	💻 CPP
🔀 Doubly LL	Insertion at K	📄 MD	💻 CPP
🔀 Doubly LL	Deletion from Head	📄 MD	💻 CPP
🔀 Doubly LL	Deletion from Tail	📄 MD	💻 CPP
🔀 Doubly LL	Deletion at K	📄 MD	💻 CPP
🔀 Doubly LL	Reverse a Doubly LL	📄 MD	💻 CPP
🎯 Medium Singly LL	Find the middle of a LL	📄 MD	💻 CPP
🎯 Medium Singly LL	Reverse a LL (Iterative)	📄 MD	💻 CPP
🎯 Medium Singly LL	Reverse a LL (Recursive)	📄 MD	💻 CPP
🎯 Medium Singly LL	Detect a Cyclic Linked List	📄 MD	💻 CPP
🎯 Medium Singly LL	Find the start of the Loop	📄 MD	💻 CPP
🎯 Medium Singly LL	Find the length of the Loop	📄 MD	💻 CPP
🎯 Medium Singly LL	Palindrome Linked List	📄 MD	💻 CPP
🎯 Medium Singly LL	Odd Even Linked List	📄 MD	💻 CPP
🎯 Medium Singly LL	Delete Nth Node from Back	📄 MD	💻 CPP
🎯 Medium Singly LL	Delete Middle Note	📄 MD	💻 CPP
🎯 Medium Singly LL	Sort Linked List	📄 MD	💻 CPP
🎯 Medium Singly LL	Intersection of Two LLs	📄 MD	💻 CPP
🎯 Medium Singly LL	Add 1 to a number in LL	📄 MD	💻 CPP
🎯 Medium Singly LL	Add two numbers in LL	📄 MD	💻 CPP
🎯 Medium Singly LL	Swap Pairs	📄 MD	💻 CPP
🎯 Medium Singly LL	Merge Inbetween Zeros	📄 MD	💻 CPP
🎯 Medium Singly LL	Delete Nodes present in an Array	📄 MD	💻 CPP
🌀 Medium Doubly LL	Delete all occurance of Key	📄 MD	💻 CPP
🌀 Medium Doubly LL	Pairs with given Sum in DLL	📄 MD	💻 CPP
🌀 Medium Doubly LL	Remove Duplicates from a DLL	📄 MD	💻 CPP
💀 Hard Singly LL	Reverse LL in a Group	📄 MD	💻 CPP
💀 Hard Singly LL	Rotate a LL	📄 MD	💻 CPP
💀 Hard Singly LL	Merge 2 Sorted LLs	📄 MD	💻 CPP
💀 Hard Singly LL	Merge K sorted LLs	📄 MD	💻 CPP
💀 Hard Singly LL	Clone a LL	📄 MD	💻 CPP
💀 Hard Singly LL	Browser History	📄 MD	💻 CPP

🔁 Recursion

Category	Problem / Algorithm	Explanation	Code
🙃 Basics	AOTI	📄 MD	💻 CPP
🙃 Basics	Pow (x, n)	📄 MD	💻 CPP
🙃 Basics	Good Numbers	📄 MD	💻 CPP
🙃 Basics	Sort Stack	📄 MD	💻 CPP
🙃 Basics	Reverse Stack	📄 MD	💻 CPP
🫨 Subsquences	Generate Binary Strings	📄 MD	💻 CPP
🫨 Subsquences	Generate Paranthesis	📄 MD	💻 CPP
🫨 Subsquences	Power Set	📄 MD	💻 CPP
🫨 Subsquences	Subsequences with Sum K	📄 MD	💻 CPP
🫨 Subsquences	Subsequences with Sum K - II	📄 MD	💻 CPP
🫨 Subsquences	Combination Sum	📄 MD	💻 CPP
🫨 Subsquences	Combination Sum - II	📄 MD	💻 CPP
🫨 Subsquences	Subsets	📄 MD	💻 CPP
🫨 Subsquences	Subsets - II	📄 MD	💻 CPP
🫨 Subsquences	Combination Sum - III	📄 MD	💻 CPP
🫨 Subsquences	Phone Number Combination	📄 MD	💻 CPP
🫨 Subsquences	Permutations of a String	📄 MD	💻 CPP
🤠 Hard	Palindrome Partioning	📄 MD	💻 CPP

📦 Stack and Queue

Category	Problem / Algorithm	Explanation	Code
🎈 Basics	Implement Stack Using Queue	📄 MD	💻 CPP
🎈 Basics	Implement Queue Using Stacks	📄 MD	💻 CPP
🎈 Basics	Valid Parenthesis	📄 MD	💻 CPP
🎈 Basics	Implement Min-Stack	📄 MD	💻 CPP
🧨 Expressions	Infix 2 Postfix	📄 MD	💻 CPP
🧨 Expressions	Infix 2 Prefix	📄 MD	💻 CPP
🧨 Expressions	Postfix 2 Infix	📄 MD	💻 CPP
🧨 Expressions	Prefix 2 Infix	📄 MD	💻 CPP
🧨 Expressions	Postfix 2 Prefix	📄 MD	💻 CPP
🧨 Expressions	Prefix 2 Postfix	📄 MD	💻 CPP
🎆 Monotonic DS	Next Greater Element (LC)	📄 MD	💻 CPP
🎆 Monotonic DS	Next Greater Element II	📄 MD	💻 CPP
🎆 Monotonic DS	Next Smaller Element	📄 MD	💻 CPP
🎆 Monotonic DS	NGE to Right	📄 MD	💻 CPP
🎆 Monotonic DS	Trapping Rainwater	📄 MD	💻 CPP
🎆 Monotonic DS	Sum of Subarray Minimums	📄 MD	💻 CPP
🎆 Monotonic DS	Astroid Collisions	📄 MD	💻 CPP
🎆 Monotonic DS	Remove K Digits	📄 MD	💻 CPP
🎆 Monotonic DS	Largest Rectangle in Histogram	📄 MD	💻 CPP
🎆 Monotonic DS	Maximum Rectangle	📄 MD	💻 CPP
🎃 Advanced	Sliding Window Maximum	📄 MD	💻 CPP
🎃 Advanced	Online Stock Span	📄 MD	💻 CPP
🎃 Advanced	The Celebrity Problem	📄 MD	💻 CPP
🎃 Advanced	LRU Cache	📄 MD	💻 CPP
🎃 Advanced	LFU Cache	📄 MD	💻 CPP

〽️ Two Pointer and Sliding Window

Category	Problem / Algorithm	Explanation	Code
🎲 Medium	Longest Substring without Repeating Characters	📄 MD	💻 CPP
🎲 Medium	Max Consecutive Ones III	📄 MD	💻 CPP
🎲 Medium	Fruits in a Basket	📄 MD	💻 CPP
🎲 Medium	Longest Repeating Character Replacement	📄 MD	💻 CPP
🎲 Medium	Binary Subarray with Sum K	📄 MD	💻 CPP
🎲 Medium	Subarrays that are Nice	📄 MD	💻 CPP
🧰 Hard	Substring w/ K Distinct Characters	📄 MD	💻 CPP
🧰 Hard	Substring w/ K Different Characters	📄 MD	💻 CPP
🧰 Hard	Minimum Window Substring	📄 MD	💻 CPP

🗻 Heaps

Category	Problem / Algorithm	Explanation	Code
🎴 Basics	About Priority Queues	📄 MD	-
🎴 Basics	Binary Min Heap	📄 MD	💻 CPP
🎴 Basics	Binary max Heap	📄 MD	💻 CPP
🎴 Basics	Is Array a Min Heap	📄 MD	💻 CPP
🎴 Basics	Min Heap 2 Max Heap	📄 MD	💻 CPP
🀄 Medium	Kth Largest Element	📄 MD	💻 CPP
🀄 Medium	Kth Smallest Element	📄 MD	💻 CPP
🀄 Medium	Sort Almost Sorted Array	📄 MD	💻 CPP
🀄 Medium	Task Scheduler	📄 MD	💻 CPP
🃏 Hard	Design Twitter	📄 MD	💻 CPP
🃏 Hard	Connect Sticks	📄 MD	💻 CPP
🃏 Hard	Kth Largest in a Stream	📄 MD	💻 CPP
🃏 Hard	Max Sum Combination	📄 MD	💻 CPP
🃏 Hard	Median in a Data Stream	📄 MD	💻 CPP
🃏 Hard	K Frequent Elements	📄 MD	💻 CPP

🤑 Greedy Algorithm

Category	Problem / Algorithm	Explanation	Code
🤧 Easy	Assign Cookies	📄 MD	💻 CPP
🤧 Easy	Fractional Knapsack	📄 MD	💻 CPP
🤧 Easy	Minimum Coins	📄 MD	💻 CPP
🤧 Easy	Lemonade Changes	📄 MD	💻 CPP
🤧 Easy	Valid Parenthesis	📄 MD	💻 CPP
🤐 Medium	N Meetings	📄 MD	💻 CPP
🤐 Medium	Jump Game	📄 MD	💻 CPP
🤐 Medium	Jump Game II	📄 MD	💻 CPP
🤐 Medium	Minimum Platforms for Trains	📄 MD	💻 CPP
🤐 Medium	Job Sequencing	📄 MD	💻 CPP
🤐 Medium	Candy	📄 MD	💻 CPP
🤐 Medium	Shortest Job First	📄 MD	💻 CPP
🤐 Medium	LRU Cache	📄 MD	💻 CPP
🤐 Medium	Insert Intervals	📄 MD	💻 CPP
🤐 Medium	Largest Number	📄 MD	💻 CPP

🌴 Binary Trees

Category	Problem / Algorithm	Explanation	Code
🌳 Traversals	Introductions	📄 MD	-
🌳 Traversals	Binary Trees in C++	📄 MD	-
🌳 Traversals	Preorder - Recursive	📄 MD	💻 CPP
🌳 Traversals	Inorder - Recursive	📄 MD	💻 CPP
🌳 Traversals	Postorder - Recursive	📄 MD	💻 CPP
🌳 Traversals	Level Order	📄 MD	💻 CPP
🌳 Traversals	Preorder - Iterative	📄 MD	💻 CPP
🌳 Traversals	Inorder - Iterative	📄 MD	💻 CPP
🌳 Traversals	Postorder - Iterative	📄 MD	💻 CPP
🌳 Traversals	Level Order - Bottom First	📄 MD	💻 CPP
🌲 Medium	Max Depth of BT	📄 MD	💻 CPP
🌲 Medium	Is BT Balanced?	📄 MD	💻 CPP
🌲 Medium	Diameter of BT	📄 MD	💻 CPP
🌲 Medium	Max Sum of Path	📄 MD	💻 CPP
🌲 Medium	Is it the Same Tree?	📄 MD	💻 CPP
🌲 Medium	Zig zag Traversal	📄 MD	💻 CPP
🌲 Medium	BT Boundary Traversal	📄 MD	💻 CPP
🌲 Medium	Vertical Traversal in BT	📄 MD	💻 CPP
🌲 Medium	Top View in BT	📄 MD	💻 CPP
🌲 Medium	Bottom View in BT	📄 MD	💻 CPP
🌲 Medium	Right Side View of BT	📄 MD	💻 CPP
🌲 Medium	Left Side View of BT	📄 MD	💻 CPP
🌲 Medium	Symmetric BT	📄 MD	💻 CPP
🌲 Medium	Invert Binary Tree	📄 MD	💻 CPP
🌲 Medium	Minimum Depth of BT	📄 MD	💻 CPP
🎋 Hard	Root to Node Path	📄 MD	💻 CPP
🎋 Hard	Lowerst Common Ancestor	📄 MD	💻 CPP
🎋 Hard	Maximum Width of BT	📄 MD	💻 CPP
🎋 Hard	Children Sum Property I	📄 MD	💻 CPP
🎋 Hard	Children Sum Property II	📄 MD	💻 CPP
🎋 Hard	All Nodes at a distance K	📄 MD	💻 CPP
🎋 Hard	Minimum Time to Burn Tree	📄 MD	💻 CPP
🎋 Hard	Count Total Nodes	📄 MD	💻 CPP
🎋 Hard	Construct BT from Inorder	📄 MD	💻 CPP
🎋 Hard	Contruct BT from Postorder	📄 MD	💻 CPP
🎋 Hard	Serialize and Deserialize	📄 MD	💻 CPP
🎋 Hard	Morris Inorder Traversal	📄 MD	💻 CPP
🎋 Hard	Flatten Binary Tree	📄 MD	💻 CPP

🦜 Binary Search Trees

Category	Problem / Algorithm	Explanation	Code
🚲 Concepts	Introduction	📄 MD	💻 CPP
🚲 Concepts	Search in BST	📄 MD	💻 CPP
🚲 Concepts	Find Min / Max	📄 MD	💻 CPP
🛼 Medium	Ceiling of K in BST	📄 MD	💻 CPP
🛼 Medium	Floor of K in BST	📄 MD	💻 CPP
🛼 Medium	Insertion into BST	📄 MD	💻 CPP
🛼 Medium	Delete Node from BST	📄 MD	💻 CPP
🛼 Medium	Find Kth Smallest & Largest	📄 MD	💻 CPP
🛼 Medium	Validate a BST	📄 MD	💻 CPP
🛼 Medium	Least Common Ancestor	📄 MD	💻 CPP
🛼 Medium	Build a Unique BST	📄 MD	💻 CPP
🛼 Medium	Inorder Succesor in BST	📄 MD	💻 CPP
🛼 Medium	Merge Two BSTs	📄 MD	💻 CPP
🛼 Medium	Two Sum IV	📄 MD	💻 CPP
🛼 Medium	Recover BST	📄 MD	💻 CPP
🛼 Medium	Max Sum in BST	📄 MD	💻 CPP
🛼 Medium	Largest BST Subtree	📄 MD	💻 CPP

💹 Graphs

Category	Problem / Algorithm	Explanation	Code
🎯 Basics	Introduction	📄 MD	💻 CPP
🎯 Basics	Graphs in CPP	📄 MD	-
🎯 Basics	Graphs in Java	📄 MD	-
🎯 Basics	Graphs in Javascript	📄 MD	-
🎯 Basics	Connected Components in Graph	📄 MD	💻 CPP
🎯 Basics	BFS Traversal in Graphs	📄 MD	💻 CPP
🎯 Basics	DFS Traversal in Graphs	📄 MD	💻 CPP
🧩 Medium	Number of Provinces	📄 MD	💻 CPP
🧩 Medium	Rotten Oranges	📄 MD	💻 CPP
🧩 Medium	Flood Fill	📄 MD	💻 CPP
🧩 Medium	Detect Cycle in Undirected Graph - BFS	📄 MD	💻 CPP
🧩 Medium	Detect Cycle in Undirected Graph - DFS	📄 MD	💻 CPP
🧩 Medium	Surrounded Regions	📄 MD	💻 CPP
🧩 Medium	Number of Enclaves	📄 MD	💻 CPP
🧩 Medium	Word Ladder	📄 MD	💻 CPP
🧩 Medium	Word Ladder II	📄 MD	💻 CPP
🧩 Medium	Number of Islands	📄 MD	💻 CPP
🧩 Medium	Bipartite Graph	📄 MD	💻 CPP
🧩 Medium	Detect Cycle in Directed Graph - DFS	📄 MD	💻 CPP
🧸 Topo Sort	-	📄 MD	💻 CPP

🎖️ Dynamic Programming

Category	Problem / Algorithm	Explanation	Code
🍭 Basics	-	📄 MD	💻 CPP

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⚛️ Development Structure

I know this might seem like a lot, but success only comes to those who persist, and don't give up. Anyway, as you progress through the foundations, the later parts become easier.

🍕 React Frontend Roadmap

Topic	Resourse	Links	Notes
HTML	Youtube - Dave Gray	YT	Do this first, learn about semantics and tags and why they are important.
CSS	Youtube - Dave Gray	YT	Get basic understanding of CSS classes, and practices with simple projects.
HTML & CSS	Youtube - SuperSimpleDev	YT	Love Simon's content, super simple, and easy to understand.
Javascript	Hitest Choudhary	YT	This is an old series by Hitesh sir, all in english, and pretty solid.
Javascript	Hitest Choudhary	YT	This series is in Hindi, more modern and simple.
Javascript	SuperSimpleDev	YT	Simon again, he is also really great, industry standard but simple.
Javascript	Dave Gray	YT	Dave is also great, but I prefered the other three above in JS.
Javascript	arindal1	repo	Elaborate notes on Javascript with code and examples.
Javascript	arindal1	repo	A 30 Day Javascript challenge, to make your foundations solid.
Git	Brendan Dickinson	YT	Short and sweet intro to Git.
Git	Nick White	YT	Simple and straight, a more casual and easy explanation.
Git	Hitesh Choudhary	YT	If you want to go in depth, with inner mechanisms and industry level standards.
NPM	Traversy Media	YT	Course to package managers for Development.
TailwindCSS	JavascriptMastery	YT	Great explanations, and hands on parctice.
TailwindCSS	Dave Gray	YT	Dave is really good with CSS, smh.
ReactJS	Hitesh Choudhary	YT - repo	Pure beginner friendly course for React. Hitesh sir is super particular about industry standards.
ReactJS	Hitesh Choudhary	YT	This series is in Hindi, equivalent to the course above.
ReactJS	SuperSimpleDev	YT	Simon is always straightforward, and tries his best to keep things simple but good quality.
ReactJS	JavascriptMastery	YT	Once you have understood basics of React, watch this.
Linters and Formatters	CoderDave	YT	Linters are fairly easy, just watch this and gain a basic understanding.
Module Bundler	Fireship	YT	You will already know about module bundlers while learning React, if not, this is for you. I find fireship really interesting.
Vite	CodeSTACKr	YT	A vite crash course to know indepth mechanisms of Vite. (optional)
Testing	dotconferences	YT	Testing is an essential but advanced part of development. This video tells you all about testing in industry.
Jest	FreeCodeCamp	YT	Jest is a Javascript testing tech.
Authentication	Hayk Simonyan	YT	Hayk Simonyan
Web API	Keep on Coding	YT	Basics of Web API.
Types of APIs	Codist	YT	Different types of APIs used in the industry, and why?
Rest API	IBM Tech	YT	A little about Restful APIs
Web Security	Arkenstone Learning	YT	This a playlist that focuses on WebSecurity through ZAP, not super important, but do learn the theory.
SSR	Microsoft Developer	YT	What is Server Side Rendering?
SSR	Smoljames	YT	Server Side Rendering vs Client Side Rendering
NextJs	FreeCodeCamp	YT	Well, if you have got your hands on React, and want to dive into SSR. Well, NextJS is the best. And... it's taught by the Head of Developer Community at Vercel!
SSG	Net Ninja	YT	Static Site Generators (SSGs) build websites as pre-generated HTML files from content and templates. Make sites fast, secure, and easy to host. (kinda optional)
Design System	Figma	YT	Well designing your site is also important.
Deployments	- Multiple -	Netlify - Github - Vercel - Render -	How to deploy your code in the Internet.
Web Performance	Dmitriy Zhiganov	YT	How to enhance the performance of your site. Design Systems.
Lighthouse	WPDev	YT	Lighthouse is an open-source, automated tool for improving the quality of web pages.
Dev Tools	Tobi Mey	YT	DevTools are a set of web developer tools built directly into web browsers.
Service Workers	Udacity	YT	Service Workers are JavaScript files that act as proxy servers between web browsers and web servers.
Accessibility	Chrome	YT	Understanding Accessibility and it's importance for websites.

that should be all for Frontend development. Rest is upto practice and projects.

🔰 Node Backend Roadmap

In progress.

🍵 Java Roadmap

Phase 1: Core JAVA + OOP

• Java memory model (Heap v Stack)
• OOP Principles
• SOLID Principles
• Generics, Lamda, Streams
• Exception Handling
• Immutibility & Best Practices
• JVM Internals

Phase 2: DSA

• FAANG Level prep
• Clean Code
• Edge-case handling
• TIME + Space Complexity

Phase 3: Multithreading & Concurrency

• Thread lifecycle
• Synchronization v Locks
• Deadlocks, Starvation
• ExecutorService
• Completable Future
• Concurrent Collections

Phase 4: Spring Boot + RestAPIs

• Spring Core & Dependency Injection
• Spring Boot auto-config
• RestAPI design
• Validation & Execution Handling
• Spring Security (JWT + Role Based)
• Logging & Monitoring
• Unit + Integration testing

Phase 5: Databses

• SQL:

  • Indexing & query optimizations
  • Joins & Subqueries
  • ACID v BASE

• NoSQL:

  • MongoDB schema design
  • when to use SQL & noSQL
  • Redis Caching

Phase 6: System Design

Below 🔽🔽

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📁 System Design Structure

Topic	Resource	Links	Notes
Introduction	Crio.do	article	Basic intro to System Design and Engineering.
Guide	Swimm	article	Basic intro to System Design and patterns.
The Primer	donnemartin	repo	The System Design Primer. It's the Holy Grail for SDEs, trust me.
SD Template	Top Cat	leetcode	A template for how to approach designing an efficient System.
SD Questions	HiredInTech	article	In this course you will see what such system design interview questions look like and what is expected from you in order to solve them.
SD Interviews	Jackson Gabbard	YT	Walk through the context and goals of a systems design and architecture interview.

[ IN PROGRESS ]

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Contact

• LinkedIn - arindalchar
• Twitter - arindal_17

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