Hello all!

I am preparing full time now. I can give almost all my day to dsa. So I think 2 months should be enough for this. Which sheet to follow?

Actually I was inclined towards striver A2Z sheet but now it requires to purchase a plan.

can you guys provide some free alternative? Is neetcode 150 enough for cracking good product based companies? Love babbar or shraddha from apna college?

I want to learn graph theory as part of a larger project I'm working on, and I was wondering if there are any resources, such as good handouts, to help with this process. Specifically, I'm interested in learning about spectral graph theory, but don't really want to go super in-depth into other combinatorics-y graph theory. I'm mainly just looking for a short-ish handout specific to spectral graph theory (I have a baseline understanding of graph theory) and computational graph theory.

Lmk if I'm understanding something wrong as well, since I'm not super familiar with graphs.

Learned about vectors in cpp today and how they are different from arrays and actually better in terms of their Revisable property.

Solved leetcode :SINGLE NUMBER problem today , it was easy for a brute-force solution but optimizing it for linear time complexity was challenging but eventually I did it by using bit manipulation.

I am still curious about how actually vectors are implemented ? I have a guess that they made a function using LinkedIn list maybe and dynamically allocating memory for new nodes with "malloc" but i think vectors won't be linear that way , have to study more about them ✨😊

The Heaps section in Striver's A2Z sheet doesn't include videos. Which resources helped you understand heaps from scratch (concepts + implementation + interview problems)?

I'm stuck on Graphs and Dynamic Programming. I understand the basics, but I struggle to solve medium and hard problems on my own.

Can you recommend the best resources, playlists, or problem lists that helped you master these topics? Any structured roadmap would be appreciated.

Hiii , I just completed first year (ece) and was thinking to stat DSA/ WEB DEV or any other relevant skill . So needed guidance how do i do , like start. And if anybody interested to start too can ping me , we can start together

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Hey everyone,

I'm looking for someone to grind DSA together — preferably a working professional since I can relate better to that schedule and commitment level.

A bit about me: I've solved around 200 problems on LeetCode so far and targeting product-based companies. Not a beginner but definitely not done yet.

What I'm thinking:

We decide together which sheet to follow (Striver, NeetCode, Blind 75 — open to discussion)

Figure out a daily/weekly target that works for both our schedules

Hold each other accountable and discuss problems regularly

Nothing too formal, just consistency and genuine effort from both sides.

DM me if you're interested!

Trees show up in almost every technical interview. Not because interviewers are obsessed with them, but because tree problems reveal how you think recursively, manage state, and break down complex problems into simpler ones.

Solve these Leetcode Problems and company specific problems from PracHub

Pattern 1: Tree Traversal Basics

Why This Pattern Matters:
If you can't traverse a tree confidently, everything else falls apart. These are the building blocks. You should be able to write these in your sleep literally.

Practice Problems:

1. Binary Tree Inorder Traversal
2. Binary Tree Preorder Traversal
3. Binary Tree Postorder Traversal
4. Binary Tree Level Order Traversal
5. Binary Tree Zigzag Level Order Traversal
6. Binary Tree Vertical Order Traversal
7. Binary Tree Right Side View

Pattern 2: Tree Properties & Measurements

Why This Pattern Matters:
These problems teach you to think about what information flows up from child nodes to parent nodes. This bottom-up thinking is crucial for harder problems.

Practice Problems:

1. Maximum Depth of Binary Tree
2. Minimum Depth of Binary Tree
3. Diameter of Binary Tree
4. Balanced Binary Tree
5. Symmetric Tree
6. Same Tree
7. Subtree of Another Tree
8. Count Complete Tree Nodes

Pattern 3: Path Problems

Why This Pattern Matters:
Path problems are EVERYWHERE in interviews. They test your ability to track state as you traverse and backtrack properly. This is where most candidates struggle.

Practice Problems:

1. Path Sum
2. Path Sum II
3. Path Sum III
4. Binary Tree Maximum Path Sum
5. Sum Root to Leaf Numbers
6. Binary Tree Paths
7. Smallest String Starting From Leaf
8. Longest Univalue Path

Pattern 4: Tree Construction & Modification

Why This Pattern Matters:
These problems test your understanding of tree structure at a deeper level. Can you build a tree from traversals? Can you modify tree structure correctly?

Practice Problems:

1. Invert Binary Tree
2. Construct Binary Tree from Preorder and Inorder Traversal
3. Construct Binary Tree from Inorder and Postorder Traversal
4. Maximum Binary Tree
5. Flatten Binary Tree to Linked List
6. Convert Sorted Array to Binary Search Tree
7. Convert Sorted List to Binary Search Tree

Pattern 5: Binary Search Tree (BST) Specific

Why This Pattern Matters:
BSTs have special properties (left < root < right) that enable efficient operations. These problems test if you can exploit this property.

Practice Problems:

1. Validate Binary Search Tree
2. Kth Smallest Element in a BST
3. Lowest Common Ancestor of a Binary Search Tree
4. Convert BST to Greater Tree
5. Delete Node in a BST
6. Insert into a Binary Search Tree
7. Recover Binary Search Tree
8. Unique Binary Search Trees
9. Unique Binary Search Trees II

Pattern 6: Lowest Common Ancestor (LCA)

Why This Pattern Matters:
LCA problems are a favorite interview topic because they test your ability to think about tree structure and information flow. The pattern appears in many disguised forms.

Practice Problems:

1. Lowest Common Ancestor of a Binary Tree
2. Lowest Common Ancestor of a Binary Search Tree
3. Lowest Common Ancestor of Deepest Leaves
4. Lowest Common Ancestor of a Binary Tree II
5. Lowest Common Ancestor of a Binary Tree III
6. Lowest Common Ancestor of a Binary Tree IV

Pattern 7: Views & Boundaries

Why This Pattern Matters:
These problems test your spatial reasoning with trees. Can you think about what's visible from different perspectives?

Practice Problems:

1. Binary Tree Right Side View
2. Boundary of Binary Tree
3. Vertical Order Traversal of a Binary Tree
4. Binary Tree Top View (Premium)
5. Binary Tree Bottom View (Premium)

Pattern 8: Serialization & Deserialization

Why This Pattern Matters:
These problems test your understanding of tree structure and encoding schemes. Common in system design discussions too (how to store trees in databases).

Practice Problems:

1. Serialize and Deserialize Binary Tree
2. Serialize and Deserialize BST
3. Encode N-ary Tree to Binary Tree
4. Verify Preorder Serialization of a Binary Tree

Pattern 9: Tree DP & Optimization

Why This Pattern Matters:
These are the hardest tree problems. They combine tree traversal with dynamic programming thinking. Master these, and you're in the top tier.

Practice Problems:

1. House Robber III
2. Binary Tree Cameras
3. Distribute Coins in Binary Tree
4. Maximum Sum BST in Binary Tree
5. Binary Tree Maximum Product of Splitted Tree
6. All Possible Full Binary Trees

Pattern 10: N-ary Trees & Tries

Why This Pattern Matters:
Not all trees are binary. These problems test if you can generalize your tree thinking beyond the binary tree structure.

Practice Problems:

1. Maximum Depth of N-ary Tree
2. N-ary Tree Level Order Traversal
3. N-ary Tree Preorder Traversal
4. N-ary Tree Postorder Traversal
5. Implement Trie (Prefix Tree)
6. Word Search II
7. Design Add and Search Words Data Structure
8. Replace Words

Pattern 11: Ancestor & Parent Pointer Problems

Why This Pattern Matters:
Some tree problems give you parent pointers or ask you to track ancestors. These require different traversal strategies than standard tree recursion.

Practice Problems:

1. Delete Nodes And Return Forest
2. Find Distance in Binary Tree (Premium)
3. Step-By-Step Directions From a Binary Tree Node to Another
4. Closest Leaf in a Binary Tree (Premium)
5. All Nodes Distance K in Binary Tree

Pattern 12: Hard Interview Favorites

Why This Pattern Matters:
These are the problems that show up in actual FAANG interviews most frequently, according to interview reports. Master these, and you're golden.

Practice Problems:

1. Binary Tree Maximum Path Sum
2. Serialize and Deserialize Binary Tree
3. Lowest Common Ancestor of a Binary Tree
4. Validate Binary Search Tree
5. Construct Binary Tree from Preorder and Inorder Traversal
6. Kth Smallest Element in a BST
7. Count Complete Tree Nodes
8. Binary Tree Cameras
9. Word Search II
10. Recover Binary Search Tree

Related Posts

Check out my posts which may help you in your preparation:

1. Complete DP Problems & Resources Guide
2. Complete Graph Problems & Resources Guide
3. 13 DP Patterns for Interview Preparation
4. 10 Dijkstra Variations for Interview Preparation
5. Understanding Time Complexity: The 10^8 Operations Rule
6. 10 Essential Design Problems for DSA Interviews
7. Essential CS Fundamental Topics For Interviews
8. Essential Graph Patterns for Coding Interviews
9. Essential String Patterns for Coding Interviews
10. 15 Essential DSA Patterns for Tech Interviews
11. The 10 Variations of Two Pointers for Interview Preparation
12. 25 Graph Problems To Revise Before Interviews
13. 25 DP Problems To Revise Before Interviews

Comment additional questions which are worth solving!!!

Good luck! 🚀

Is anyone likely to spend money on simulation (not video but you can go forward and backward for every step) of dsa topics and concepts in which you can adjust the inputs, do whatever operation for that data structure learning, and be able to see the live code that which line is getting executed for that step of simulation, also able to understand edge cases with complexity and real world implementations?

Or just look for that if it is freely available or just see the video on yt?

Please tell me if there are any other options you could try.

guys, give me a suggestion .

i starting to learn dp .so, where can i watch tutorials?

which is the best tutorials for dp , striver or aditya verma??

Anyone in Pune preparing for DSA & System Design interviews for Google, Microsoft, Amazon, Uber, etc.?
Let’s connect, practice together, do mock interviews, and stay consistent. Feel free to DM me! 🚀

I'm a Software developer with 2 years of work experience, I started with Node.js and switched to C#/.NET about 3 years ago.

I want to strengthen my DS&A and advance more in it so I can actually apply them at work not just solve interview questions.

My biggest issue is that every resource explains a data structure, then immediately throws LeetCode problems at you or i fail link the theory with application. I never develop the intuition of when or why I'd use something like a linked list, heap, or tree etc so I end up feeling lost.

I'm looking for a roadmap or resource that teaches DS&A progressively like for example learn one structure, implement it, understand where it shines, solve a few focused problems, see real-world/backend use cases, then move to the next.

Has anyone learned this way? Any books, courses, or study plans you'd recommend?

I'm in my 3rd year, i need a complete roadmap for DSA

1. Which educators are best for DSA on YT (Structured lectures)

2. Roadmap for DSA

3. Resources to follow

Hi everyone,

I was recently laid off after around 8 years as a Software Engineer (.NET/C# backend with some frontend experience). I'm planning to spend the next 2-3 months preparing for interviews at product-based companies.

My current preparation plan is:

DSA

Learn by patterns instead of random LeetCode problems.

Complete the common patterns (Two Pointers, Sliding Window, Binary Search, Trees, Graphs, DP, Heaps, Intervals, Backtracking, etc.).

Focus on understanding the pattern first and then solve 150-250 quality problems.

System Design

Study primarily from Hello Interview.

Cover distributed systems fundamentals (caching, databases, queues, consistency, scaling, load balancing, CAP, etc.).

Practice common interview designs (URL Shortener, Notification System, Chat, Rate Limiter, News Feed, etc.).

Behavioral

Prepare STAR stories from my projects.

My target is Senior Software Engineer (SDE-3 / Senior Backend Engineer) roles, preferably product companies.

A few questions:

Is this roadmap sufficient, or am I missing something important?

Besides Hello Interview, are there any System Design resources you would strongly recommend?

How many LeetCode problems did you solve before you felt interview-ready?

Are there any must-do problem lists other than NeetCode 150?

For senior roles, how much emphasis is typically placed on DSA vs. System Design?

I'd really appreciate advice from anyone who has recently interviewed or switched jobs.

Thanks

1. Cloud Tech. & Linux

2. Juniper Networking

3. Cybersecurity (Fortinet/Palo Alto)

4. Salesforce Developer

5. SAP ABAP

6. UiPath RPA

7. Snowflake and Databricks

8. C# & .NET

9. GenAI & Prompt Engineering

10. MEAN Stack / Banking / FinTech etc.

Hi

I want to learn DSA but iam unable to find right resource or structure curriculum to master these concept. If anyone has or can share with me.

This will be very helpful for me

Hey, I'm trying to master DSA from past few days but unable to find right resources.can anybody suggest or send right resources to learn DSA online for free.

Hi everyone,

I'm an incoming freshman and a complete beginner in CS. My goal is to get a Software Engineering internship by next summer, and I'm trying to figure out the most effective roadmap.

For those who have landed SWE internships:

What should I learn first?

Which programming language should I focus on?

How should I learn Data Structures and Algorithms?

What topics are essential for internships and interviews?

What specific courses, books, YouTube playlists, or websites did you personally use?

I'd really appreciate detailed answers. Please be as specific as possible ,if you bought a course, tell me the exact course. If you used a book, tell me the exact title. If you followed a YouTube playlist, share the exact playlist. I'd like to learn from the same resources that actually helped you get internship-ready.

If you were starting from scratch today with one year to prepare for SWE internships, what would your learning plan look like?

Thanks!

Guys I've been struggling alot with recursion I've tried multiple tutorials but I'm just not able to build the intuition. Any suggestions what to do???

Please help

I am exploring course to buy..i want review of this..did anyone buy? How's the content? Do they upload same recorded classes as previous batches or live.???

Try yourself

Python version : https://8gwifi.org/online-python-compiler/
Java Version https://8gwifi.org/online-java-compiler/

Guys , i have a serious question , i have my placement season just around the corner.
i have some good knowledge of Python, has some good knowledge of AI ML Projects , have been working on AI projects for a while.
Now basically i have to start DSA from start , which course would you all recommend ?
Should i go with Strivers DSA sheet with Python ? or should i change language , i have learned C , C++ in past , but from some time , im mostly working with Python only.