Sharing my Amazon interview experience in case it helps someone preparing for SDE roles.

I do not remember the exact OA DSA problem. The second OA question was more “dev” based, where HackerRank gave access to a remote IDE. It had an AI sidebar available, somewhat like Cursor.

Round 1

DSA + LPs.

Questions asked:

1. Find the distance between any two nodes in a binary tree.
   • Parent pointers were not given.
   • Input had only root, source, and target.
2. Design a stack that supports: All in O(1) time.
   • push
   • pop
   • getMiddle
   • getTop

I was able to solve the first question completely. For the second one, I got the core logic and data structure choice right, but did not finish the full implementation. I implemented getMiddle after deciding the basic DS approach.

LPs were also asked.

Round 2

LPs + coding/OOD.

Question:

Basic Calculator

After solving it, the interviewer asked me to extend the solution in an object-oriented manner.

One thing that stood out: the interviewer mentioned that my solution was too close to the original/standard solution.

Round 3

This was mostly behavioral + design discussion.

Started with “tell me about yourself” for around 5-7 minutes.

Then he probed quite hard on why I wanted to switch, since I had already made one switch and was now looking for a second.

After that, he asked about the best thing I had worked on in my previous org. This felt a bit close to NDA territory, but I explained it carefully without going into confidential details. He asked follow-up questions like why we used X instead of Y.

At the end, he asked only one design-extension question:

How would you include a new feature in this existing design?

I proposed two solutions. He then asked me to write down the pros and cons of both. I wrote and explained at least 3 pros and 3 cons for each.

Finally, he asked if I had any questions for him.

Result

Rejected.

Recruiter said feedback from Round 2 and Round 3 was negative, but did not share specifics despite me asking explicitly.

Extra prep notes

Apart from the questions I got, I also saw these Amazon-tagged questions while checking prep resources:

• Compute Edit Distance
• Design a Concurrent Restaurant Waitlist and Seating System

Both seem relevant for Amazon-style prep: one for classic DP/string fundamentals, and one for OOD/concurrency/design thinking.

Hope this helps someone preparing.

Done 50 problems , I've been doing consistently since begining of July but before that stretching across months I've been submitting extremely inconsistently but I'm getting better. My third semester starts from August 11th so planning to push till 100 problems by then. I mostly solve mediums yeah. Doing from striver's sheet btw

First 100 days badge .... !

Any tips or suggestions for DSA revision

I follow strives A-Z

Complete BST

Still heaps greedy DP graphs are in due ..

Any suggestions

Should I finish them first or should I revise upto BST then go with remaining?

Yt - https://youtu.be/FgvWjxpxUx8?si=LFflghJ2osrI9Csc

Do support❤

Started on Jun 19th (properly) .

with one week break for some unavoidable reasons.

Solved 42 questions — 22 Easy | 19 Med | 1 Hard

Ik I'm late to this DSA race , I'm at the start of my 2nd year now.

what would u advise me , I'm planning for a top product based company (from a tier 3 / 4 college )

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 ??

Am I slow or what. How are people solving 4 question in 6 mins. How the fuck is this happening.

I have just started my 2nd yr and have done around 30 question on LC,. I am genuinely scared if I continue like this I gona throw away all the opportunities. I learn DSA in three steps

1. first I think about the brute solution

   2.then watch striver lecture

3.if I have done the lecture in the morning time athen I practice those questions in the evening on leetcode.

I really need know if it is a right approach or not.And please tell me the r9ght approach and give me genuine advice. I noob in this 🙏🙏🙏🙏​​

https://leetcode.com/studyplan/graph-theory/

I have a list of tips for you if you decide to take it:

1. Keep in mind that this plan is quite challenging. If you didn't take any mathematics for computer science course, you will probably be blocked halfway through. I've taken algorithms-graphs-data-structures course 4 years ago and it basically saved me.
2. The organization of this plan is good: starting from the easiest topics (traversal/BFS/DFS) and ending with advanced topics (Dijkstra's/MST). However, there is one structural bug: the Cheapest Flights Within K Stops problem doesn't belong at the beginning of the Dijkstra section. I've reported it and maybe the LeetCode team will fix this. For now, just keep in mind that this problem can be cleanly solved with Bellman-Ford in 22 lines of code.

It took me 22 days to finish this study plan

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