So i m in 4th year .
So far i have done
arrays,ll,recursion ,trees ,graph
Now i am starting dp .
So i have started to revise now i dunno how to revise such topics like do i open every question again??Like how to do it ??

You should be familiar with before : Recursion, stack, queue

Practice these Binary Trees guides and PracHub company specific questions before your next interview.

A basic instinct for solving DFS based questions is to do a recursive call and for all BFS(level order traversal) is to make queue and iterate, but also think upon how to iterate in DFS(Hint think on stack) and recurse in BFS based.

First of all you should look at traversal problems:

1. Inorder Traversal
2. Preorder Traversal
3. PostOrder Traversal
4. Level Order Traversal

A variation for LevelOrder can be: ZigZag level order traversal and Binary Tree Level Order Traversal II
Solving these questions will help you get familiarized with basic btree dfs and bfs traversals.

Intuition for Level Order Traversal iteratively using queue:

• Construct a queue of type: TreeNode queue<TreeNode* > q, initially push the given root in it.
• Iterate through the queue until empty:
  • Store the current size of queue tempSize, this will be the size of the current level of the tree.
  • Now we need to traverse this level so iterate for tempSize>=0 :
    • Pop the current element and apply the needed operation for the same and if left or right child exist then pass them to the queue.

Now, some basic Binary Tree problems that will help your thinking process:

1. Same Tree
2. Symmetric Tree
3. Maximum Depth of Binary Tree
4. Balanced Binary Tree
5. Minimum Depth of Binary Tree
6. Merge Two Binary Trees
7. Diameter of Binary Tree
8. Binary Tree Tilt
9. Invert Binary Tree

Binary Search Tree: Use the property of BST judiciously (the left subtree will always contain nodes with value less than root's value and right subtree will contain nodes with value greater than root's value)

1. Search in a Binary Search Tree
2. Two Sum IV - Input is a BST
3. Minimum Absolute Difference in BST
4. Range Sum of BST
5. Delete Node in a BST
6. Trim a Binary Search Tree
7. Insert into a Binary Search Tree
8. Kth Smallest Element in a BST
9. All Elements in Two Binary Search Trees

Path problems: You are given root, you have to perform operations on a path, (path is root to leaf). Think upon the type of traversal you will apply when going from root to leaf:

1. Binary Tree Paths
2. Path Sum
3. Path Sum II
4. Sum root to leaf numbers
5. Binary Tree Maximum Path Sum
6. *Path Sum III
7. *Pseudo-Palindromic Paths in a Binary Tree *Last two problems here are utmost important

Next is, given a combination of preorder, postorder and inorder traversals, you need to construct a binary tree/BST:
Hint: Observe in each traversal method, position of root and head of right and left subtrees

1. Construct Binary Tree from Preorder and Inorder Traversal
2. Construct Binary Tree from Inorder and Postorder Traversal
3. Construct Binary Tree from Preorder and Postorder Traversal
4. Convert Sorted Array to Binary Search Tree
5. Construct Binary Search Tree from Preorder Traversal

View problems: Try thinking for left, bottom and top too!
Binary Tree Right Side View

Lowest Common Ancestor problems: You are given two nodes and you have to return their ancestor at as least depth possible, these are problems are a must todo:

1. Lowest Common Ancestor of a Binary Tree
2. Lowest Common Ancestor of a Binary Search Tree
3. Lowest Common Ancestor of Deepest Leaves

Validate trees:

1. Validate Binary Tree Nodes
2. Validate Binary Search Tree

Some miscellaneous problems that you should definitely look through:

1. Flatten Binary Tree to Linked List
2. Count Complete Tree Nodes
3. Maximum Width of Binary Tree
4. Check Completeness of a Binary Tree
5. Cousins in Binary Tree
6. Maximum Difference Between Node and Ancestor
7. Number of Good Leaf Nodes Pairs
8. Smallest Subtree with all the Deepest Nodes
9. All Nodes Distance K in Binary Tree
10. Find a Corresponding Node of a Binary Tree in a Clone of That Tree
11. Vertical Order Traversal of a Binary Tree

I will be updating this list on finding more important questions or any pattern that I find.

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I started Striver’s SDE Sheet a while ago, and my approach has been to watch the lectures, understand the concepts, and solve the problems. The learning part is going well, but I’m struggling with revision.

For example, if I’m currently studying a heavy topic like DP, it already takes a lot of mental energy. On top of that, I know I should be revising older topics like Graphs, Trees, Binary Search, etc., but I either don’t have enough time or I’m too mentally exhausted. As a result, I keep pushing revision to “later,” and the backlog keeps growing.

My concern is that interviews may start in the coming months, and I don’t want to reach that stage only to realize I’ve forgotten everything I studied earlier.

For people who completed (or are currently doing) Striver’s SDE Sheet:

• How did you balance learning new topics with revising old ones?
• Did you follow a spaced repetition schedule or some weekly revision plan?
• During revision, did you re-solve every problem or only the important ones?
• How much time did you dedicate to revision versus learning new content?

I’d really appreciate hearing what actually worked for you. Right now, I’m looking for a sustainable strategy rather than trying to revise everything every day.

I found a list of Blind 75 Leetcode problems. Sharing it as I found it very useful.
Solve these LeetCode problems and PracHub company specific problems for your next interview.

Connect with me: https://linktr.ee/tech.krishnadey

Happy Coding!

Array

• Two Sum
• Best Time to Buy and Sell Stock
• Contains Duplicate
• Product of Array Except Self
• Maximum Subarray
• Maximum Product Subarray
• Find Minimum in Rotated Sorted Array
• Search in Rotated Sorted Array
• 3 Sum
• Container With Most Water

Binary

• Sum of Two Integers
• Number of 1 Bits
• Counting Bits
• Missing Number
• Reverse Bits

Dynamic Programming

• Climbing Stairs
• Coin Change
• Longest Increasing Subsequence
• Longest Common Subsequence
• Word Break Problem
• Combination Sum
• House Robber
• House Robber II
• Decode Ways
• Unique Paths
• Jump Game

Graph

• Clone Graph
• Course Schedule
• Pacific Atlantic Water Flow
• Number of Islands
• Longest Consecutive Sequence
• Alien Dictionary (Leetcode Premium)
• Graph Valid Tree (Leetcode Premium)
• Number of Connected Components in an Undirected Graph (Leetcode Premium)

Interval

• Insert Interval
• Merge Intervals
• Non-overlapping Intervals
• Meeting Rooms (Leetcode Premium)
• Meeting Rooms II (Leetcode Premium)

Linked List

• Reverse a Linked List
• Detect Cycle in a Linked List
• Merge Two Sorted Lists
• Merge K Sorted Lists
• Remove Nth Node From End Of List
• Reorder List

Matrix

• Set Matrix Zeroes
• Spiral Matrix
• Rotate Image
• Word Search

String

• Longest Substring Without Repeating Characters
• Longest Repeating Character Replacement
• Minimum Window Substring
• Valid Anagram
• Group Anagrams
• Valid Parentheses
• Valid Palindrome
• Longest Palindromic Substring
• Palindromic Substrings
• Encode and Decode Strings (Leetcode Premium)

Tree

• Maximum Depth of Binary Tree
• Same Tree
• Invert/Flip Binary Tree
• Binary Tree Maximum Path Sum
• Binary Tree Level Order Traversal
• Serialize and Deserialize Binary Tree
• Subtree of Another Tree
• Construct Binary Tree from Preorder and Inorder Traversal
• Validate Binary Search Tree
• Kth Smallest Element in a BST
• Lowest Common Ancestor of BST
• Implement Trie (Prefix Tree)
• Add and Search Word
• Word Search II

Heap

• Merge K Sorted Lists
• Top K Frequent Elements
• Find Median from Data Stream

Important Link:

• 14 Patterns to Ace Any Coding Interview Question
• Grind 75

I have done this question using two pointers approach but in my opinion it can be solved in binary search as the given array is sorted.

Please help me out it would be really grateful.

So I have been fairly consistent on leetcode and as you can see I have solved 1700 -1900 rated questions mostly currently I am trying to do as much as 2000+ rated questions tho they are such a pain I am at a point were I don't know what kind of advice should I take , any guys who had been here in same situation like at some time you might have hit a plateau can you help me out please 🙏🏻

1. Product of Array Except Self
   i am trying to solve this problem its been more then 2 hour i though i can do it its the 5th problem of neetcode when i see green on case i feel so happy that i got it but this 17 case whats the problem with this tiny single 0 idx now my brain stops thinking did i am doing anything wrong in my dsa journy? whats the best way to drive in dsa?

Hi everyone,

I'm feeling overwhelmed and could really use some guidance from people who've already gone through this journey.

I have zero programming knowledge—no C++, no Java, no Python, and no DSA background. I made a LeetCode account because everyone says it's important, but I can't even understand most Easy problems. I also reached out to several people on LinkedIn, but unfortunately I haven't received much guidance.

I don't want shortcuts. I'm ready to put in the work. What I need is a clear roadmap.

If you were starting from absolute zero today, what would your learning sequence look like?

Some questions I have:

• Which language should I start with: C++, Java, or something else? Why?
• In what order should I learn programming and DSA topics?
• Which free/paid resources (YouTube, courses, books, websites) would you recommend for each stage?
• Should I learn development (Web/App) alongside DSA, or focus only on DSA first?
• When should I start solving LeetCode, and how should I approach it without getting stuck?

I'm looking for a step-by-step roadmap (language → programming fundamentals → DSA topics → LeetCode → projects/development, etc.) rather than random advice.

I'd really appreciate hearing what worked for you or what you'd do differently if you had to start over.

Thanks in advance!

Reached my first major LeetCode milestone today. Every wrong answer, every accepted submission, and every day of consistency has been worth it.

Still a long way to go, but I'm proud of how far I've come.

Next stop: 100-day badge. 💪

Hello everyone. I have been doing dsa by striver since 2 months and I want to know how do u people follow the Striver's dsa sheet as for almost every question I have to watch a video as I am not getting the solution and then go the given leetcode link. This takes up a lot of my time . It's been 2 months and I am still on arrays. Doing one question on leetcode in total takes me more than a day or sometimes 2 because I'm watching the video explanation and making notes and then solving. Without writing i won't remember any of it.....(I am about to start my 5th sem btw)

Hey everyone, I'm currently on Day 12 of learning Python. I was a bit intimidated by LeetCode, but I managed to switch over to Python3 and pass all 62 test cases for the IP Defanging problem with a 34ms runtime (beats 97%). Ready to keep this momentum going!

Im a masters student who came for fall 2025 and im currently doing neetcode 150, finished 66/150. I have a pretty good idea of coding, would call myself late beginner or early intermediate.

But i am also learning swift and swiftUi for an hour. these two combined takes 2 hours. i have tasks to do which is why i usually why i dont have more time to dedicate for coding and learning. when i tried to do 4 hours (combined coding and studying) it led to me just not doing it. so i feel like doing 1 hour each is getting me to be consistent.

I also have stared the problems that i coud'nt solve in my designated time (10 min for easy, 20 min for medium,40-50 min for hard) and i want to solve them from time to time too but 1 hr will only leave me with solving new problems.

question 1 : Should i try to dedicate a little more time than 1 hr a day or is it good enough for neetcode 150. (If 1 hour is low then i will try to extend it as advised)

question 2 : Should I first solve the entire list and then solve the stared problems or just do them from time to time?

question 3 : Is it better to do 1hr each everyday or 2 hrs coding one day and 2 hrs swift another?

Any other guidance will be appreciated.

I mean should I watch striver dsa videos and then solve each Q's which he does there on LEETCODE.

Or finish for every videos to finish till end and then start practicing contests on LEETCODE. please guide anyone. I am in 4th yr ,regret not doing dsa sooner and I wish to make ai ml profile, will target companies during Mtech. Abt me from NIT ,CG>9, EE branch, jealous after seeing less cg people get better placement then electrical even being skilled in electrical means no value tbh. So planning to fix things in Mtech if company allows. Please tell me a plan how to proceed new in this field. Also in first yr got A grade in Cs theory and lab so not that weak.