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Amazon Final Interview Questions

 

A copy of my personal incomplete list of questions I found on Amazon's Interview process from end of 2020 - 2022..
Purposely very verbose so as to allow to find the original post (via google search).
Feel free to comment missing questions so that I add them to the list.

 

Onsite

 

All Combined 2021 | SDE & New Grad

 


Tips

  •  

    I feel like to pass the onsite interview, you must demonstrate stong leadership principles and communication skills. The problems weren't too hard so I'm guessing they're looking to see if you can clearly explain your thought process.

     

  •  

    I personally think I will not get the offer because from my experience you either have to get everything perfect or you will fail. For me I can only say 2/4 interviews went perfectly thus I probably will get rejected. Alas, I do have another final round interview this August so I have another chance.

     

  •  

    One Leetcode Medium Question. Rather than the actual code, they were mostly interested in how I approach the problem and I had to speak aloud about my thought process in solving the problem. Heard back within 3 business days that they would like to extend the offer. If you practice Leetcode with full concentration then there is no reason not to clear the interviews at big companies. With regards to LP, if you have 2 scenarios which you can explain in detail for each of the LP principles, you are golden. All the best for everyone who is preparing.

     

  •  

    Finally, one last piece of advice. Please, PLEASE, avoid remembering the exact questions, but rather focus on learning the actual patterns, data structures, and logic behind each exercise.

     

  •  

    Experience -

     

    1.  

      Initial 20 minutes they will ask you LP questions only. Its not like they will ask just one or two questions on LP.

       

    2.  

      Next 20 minutes will be dedicated to coding. Links to coding platform will be shared. They wont be able to compile the code, but will see the way you are coding. One thing common in all rounds were they wanted me to write the code in OOD format. It was not like i just wrote the method and its done. They wanted me to write the object creation, function calls etc. I was not done with full implementation in round 1 and round 3, they stopped me like 2 minutes before 20 minutes are completed and asked me to write the OOD format for whole code.

       

      NOTE - I was not able to complete full implementation but i explained the approach very well, step by step. Its okay to go back and forth sometimes, just tell them i am thinking out loud, i am making connections to find optimal way :)

       

      3 Last five minutes were just if i have any questions for them.

       

  •  

    Finally I would suggest anyone who is appearing for the Amazon technical interview to focus on proper naming of variables and code readability and reusabality aspects as well.

     

by Expert (111,270 points)
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I've compiled a list of questions people have been asked for Amazon who have had 3 virtual interviews for SDE 1:

 

  • Two Sum (#1)
  • Median of Two Sorted Arrays * (#4)
  • Longest Palindromic Substring (#5)
  • String to Integer (atoi) (#8)
  • Integer to Roman (#12)
  • Roman to Integer (#13)
  • Valid Parentheses (#20)
  • Merge K Sorted Lists (#23)
  • Valid Sudoku (#36)
  • Combination Sum (#39)
  • Permutations (#46)
  • Merge Intervals (#56)
  • Rotate List (#61)
  • Minimum Path Sum (#64)
  • Word Search (#79)
  • Validate Binary Search Tree(#98)
  • Same Tree ~ (#100)
  • Symmetric Tree ~ (#101)
  • Binary Tree Level Order Traversal (#102)
  • Convert Sorted List to Binary Search Tree (#109)
  • Populating Next Right Pointers in Each Node (#116)
  • Best Time to Buy and Sell Stock (#121)
  • Word Ladder II (#126)
  • Word Ladder (#127)
  • LRU Cache (#146)
  • Min Stack (#155)
  • Number of Islands (#200)
  • Course Schedule (#207)
  • Course Schedule II (#210)
  • Add and Search Word - Data structure design (#211)
  • Word Search II (#212)
  • Integer to English Words (#273)
  • Game of Life (#289)
  • Find Median from Data Stream (#295)
  • Longest Increasing Subsequence (#300)
  • Design Tic-Tac-Toe (#348)
  • Pacific Atlantic Water Flow (#417)
  • Minesweeper (#529)
  • Diameter of Binary Tree (#543)
  • Reorganize String (#767)

 

*not required to solve
~solve both iteratively and recursively

by Expert (111,270 points)
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by Expert (111,270 points)
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by Expert (111,270 points)
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  • given a list of unique strings, if the last char at string A match first char at string B then you can append them together: good+dog -> goodog . Now return the longest possible string (length of concatenated String, not the string number). https://leetcode.com/discuss/interview-question/250623/Onsite-question-for-Amazon-String-concatenation(Updated)/246655

     

  •  

    Convert BST to Doubly Linked List without deforming tree and without using extra space except used for creating List. So this shouldn’t be done inplace.Time and Space Complexity of my solutions -: O(n) & O(1) respectively

     

  •  

    You are given a subarray which has only 0’s and 1’s , Maximise the subarray containing 1’s and in this you can only flip one 0 , tell the index of that 0Similar to thisfind-zeroes-to-be-flipped-so-that-number-of-consecutive-1s-is-maximizedon GFGTime and Space Complexity of my solutions -: O(n) & O(1) respectively

     

  •  

    Given 2 large files say file1, file2 consisting of strings of customerid - find the unique customers present in those files. Basically unique words (ex. customer1, customer 3, customer5 and so on)!

     

    My approach - Solved using HashSet but interviewer told it won't work as input is very large and Set would exceed Memory limit. I told maybe something like divide and conquer but wasn't able to come up with the actual solution.

     

  •  

    For SDE I found Amazon mostly ask Graph Medium questions for example:

     

    323. Number of Connected Components in an Undirected Graph

     

    547. Number of Provinces

     

  •  

    http://leetcode.com/problems/generate-parentheses

     

  •  

    This Question I have not seen in any platform. So I will be giving the question description. We have been given a string with parenthesis and characters in between. The parenthesis can be invalid also if it's invalid we have to return -1 and if it's valid then we need to find the maximum depth of the brackets.For eg. let s = "((((X))(((Y)))))" Output will be 5 in this caseThe string can have characters in between the brackets and it can be without characters in between also. I gave him the approach and after the initial discussion, he told me to optimize the space for validity checking of the brackets. After more discussion, I came with an optimized approach and he told it to code it. I wrote the code along with the time and space complexity.

     

  •  

    https://leetcode.com/discuss/interview-question/995825/amazon-onsite-sql-library

     

  •  

    implement business logic for amazon products with friends. Writing a function like you would in a work style

     

  •  

    for the given binary tree find the distance or number of hop required to move from one node to another.

     

  •  

    https://leetcode.com/problems/frog-jump SDE 2

     

  •  

    https://leetcode.com/problems/sliding-puzzle/ SDE 2

     

  •  

    Write a program to print the sum of two roman numbers

     

  •  

    https://leetcode.com/problems/best-time-to-buy-and-sell-stock If there is a tie, then return the minimum days to finish the transaction. Example: [1 2 3 1 3], we can buy at index 0 and sell at 2, the profit is 2. but we can also buy at index 3 and sell at 4 which only takes 2 days. So return [3, 4]

     

  •  

    describe the differences between Set, Map, Array, List and which data structure should be used with different scenarios

     

  •  

    https://leetcode.com/problems/k-similar-strings/

     

  •  

    We are given a list of cars, and the direction of the road they are in. We need to find the order in which cars leave the intersection. The list of cars have the cars at the intersection in order. However, if two cars are in opposite direction, for example East/West or North/South, they can leave the intersection even though other cars arrived before it.

     

  •  

    Given a list of inputs in the form of a string array, for example [["Item: Bread", "Id:1"], ["Item: Meat", "Id:3"], ["Item: Sauce", Id:2], ["Item: Bread", "Id:4"]], we need to arrange the input string in order and output the result. The interviewer said do not worry about parsing the string. I gave the solution of sorting based on Id and then getting the result. It was very unclear what the interviewer was expecting. Also, I made the mistake of having only screen, and the interviewer said he was nodding to my questions, and I was writing code in another window. This was a very uncomfortable interview.

     

  •  

    Write an API for Linux find command. It was this exact question: https://leetcode.com/discuss/interview-question/369272/Amazon-or-Onsite-or-Linux-Find-Command

     

  •  

    https://leetcode.com/problems/russian-doll-envelopes/

     

  •  

    https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iii/

     

  •  

    A variation of meeting rooms: https://leetcode.com/problems/meeting-rooms/Given a list of meeting rooms and a meeting reservation request. Find if the reservation request can be fulfilled or not.Follow up: What if the list of meeting rooms is sorted?Edit: I found a similar one here: https://leetcode.com/problems/my-calendar-i/

     

  •  

    Coding: create stack with O(1) push, pop and min.

     

  •  

    K most frequent items(item_id) in a stream. Input is a stream of (item_id,timestamp).

     

    Then, Interviewer asked me to find frequent items in last hour given a timestamp.

     

    For example, Given time 6:07 PM, Return k most frequent items from 5:07 PM to 6:07 PM.

     

    Gave an answer using queue, hashmap and min-heap, Not an optimal answer, But it worked.

by Expert (111,270 points)
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  • Design a restaurant table booking system with the following specifications:

     

    • The restaurant has X tables of size 2, Y tables of size 3 and Z tables of size 4.
    • There are 3 slots from 6:30 pm to 11 pm, each of 1.5 hrs.
    • Restaurant can take bookings upto 7 days in advance.
    • No two parties will share a table.
    • A pack of size N should always be assigned the largest table available.
    • Wastage of seats should be minimised.
    • Provide the database structure to support the above constraints (space should be optimised).
    • Provide an algorithm to allot table to an incoming reservation with the following specs:
      • Allot table(s) to a group of N people for the ith day and the jth slot.
    • Provide pseudo code for the algorithm stated above.
  •  

    Search for smallest element in sorted rotated list

     

  •  

    Tell me about a situation when you had a tight deadline and what are the sacrifices you made to achieve the deadline.

     

  •  

    TTL LRU Cache.
    https://leetcode.com/discuss/interview-question/284925/ttl-lru-cache

     

  •  

    Tell me about a time you couldn't finish your task within the given deadline.

     

  •  

    flatten a hierarchical linked list.

     

  •  

    A variant of topological sort in a graph.

     

  •  

    Find smallest +ve missing integer from given array without extra space.

     

    (follow up : Array can contain both positive and negative numbers).

     

    Ex : ar [1,9,8] output :2

     

  •  

    You have locking suitcase system (the one in which there will be number codes). Find the minimum number of steps to reach from given number to target number. You can move any place digit at a time. (for n-digit codes, discuss complexity). Ex : start : 0-0-1Target : 1-0-0 min steps = 2 …..changing an xth place digit by b will be counted as b steps. follow -up...what if you are not allowed to use certain numbers(not digits but whole number )(given as array)Ex: [100,234,115]

     

  •  

    Implement a custom collection class with add, remove and getRandomOperations in O(1) time

     

  •  

    https://leetcode.com/discuss/interview-question/1586723/amazon-sde-3-interview-question

     

  •  

    https://leetcode.com/discuss/interview-question/system-design/685338/microsoft-onsite-design-the-t9-predictive-text-algorithm-and-system (not sure)

     

  •  

    https://kobejean.github.io/algorithms/2020/03/08/the-award-budget-cuts-problem/

     

  •  

    Poker Cards Game

     

    As we all know that poker cards have four suites: Spades, Hearts, Clubs and Diamonds with figures from 1 to 13.

     

    Now you are given a set of poker cards, you can pick any one card as the first card. And except for the first card, you can only pick the card that has the same suit or figure with the previous one.

     

    Return the max number of cards you can.

     

    For example: [(H, 3), (H, 4), (S, 4), (D, 5), (D, 1)], it returns 3 as follows: (H,3)-->(H,4)-->(S,4)

     

    https://leetcode.com/discuss/interview-question/1030942/Amazon-Onsite-Inteview-Poker-Cards-Game

     

  •  

    Given a game board| B ||A | C | D||E | F | G ||H | I | J|Rules of movinga. you can not move to same row.b. you can not move in same column.Given a starting point and number of moves tell the number of possible options https://leetcode.com/discuss/interview-question/1170079/amazon-onsite-imdb-team

     

  •  

    Given an array of integers(pos/neg) in sorted order, return an array of elements square in sorted order.

     

  •  

    Given an array of wine prices, any given year you can sell a bottle of wine only from either of the ends. Bottle of wine increases every year. Find max profit after selling all.

     

  •  

    Given a uni-directed graph with numbers find maximum root to leaf sum with using only internal data structure.

     

  •  

    https://leetcode.com/problems/binary-tree-maximum-path-sum/

     

  •  

    https://leetcode.com/problems/word-break/

     

    Given a dictionary of words and a string, state if the string if broken into multiple words consists of dictionary words.

     

    I explained him the standard solution using BFS which is O(n) time ans O(n) space.However, the interviewer was deeply interested with me solving the question via making a Graph and then solving it.

     

    https://leetcode.com/discuss/interview-question/600412/Amazon-onsite

     

  •  

    A very similar question to this , same concept of BFS will applyGiven a 2D grid, each cell is either a zombie 1 or a human 0. Zombies can turn adjacent (up/down/left/right) human beings into zombies every hour. Find out how many hours does it take to infect all humans?https://leetcode.com/discuss/interview-question/411357/ Amazon | OA 2019 | ‍♀️ Zombie in Matrix - LeetCode Discuss

by Expert (111,270 points)
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  •  
  • Three sum

     

  •  

    Round 1 - 2 interviewers https://leetcode.com/discuss/interview-experience/1060893/Amazon-SDE-new-grad-2021-Dublin-Experience-or-Offer/854173

     

    • Implement queue using stack
    • Find loop in single linkedlist
    • find missing element in an array
    • Explain any sorting algorithm
    • Time and space complexity for the above problems
    • Difference similarity between list, linkedlist and array
    • Implementation of Hashmap
    • Difference between set, hashmap, list
  •  

    Round 2 - 1 inerviewer

     

  •  

    Round 3 - 1 interviewer

     

    • Print matrix spirally. Time and space complexity for the above problem
  •  

    Given an array of large numbers and a number K, give an algorithm to search for a triplet whose sum is K. You can modify the array. You can print any triplet whose sum is K.

     

  •  

    After basic introduction, the interviewer asked me questions about Hashmaps. such as time complexity and how to handle collisions. And he asked me how would I implement a structure to store contact informations(phones numbers, names and area codes). I think I did ok in this part, and the interviewer agreed with me on how I would use a hashmap to do so.

     

  •  

    https://leetcode.com/problems/valid-parentheses/

     

  •  

    Merge List + find Top K Elements , I solved this using a Heap to merge the Lists, and a later variation involved using BFS, basically the question was , Recommend a user features that are used by friends and friends of friends N - level deep. Given an api which can give you user's friends and friends most used features.

     

  •  

    https://leetcode.com/problems/number-of-islands/

     

  •  

    https://leetcode.com/problems/knight-probability-in-chessboard/

     

  •  

    Given a positive integer N, and a starting point 1 one can perform any of the following 2 operations in one step: https://leetcode.com/discuss/interview-experience/906535/amazon-sde-i-bangalore-october-2020-offer

     

    • Add 1 to the number
    • Double the number

     

    The task is to find the minimum number of steps to reach N (desired complexity O(log n)).

     

  •  

    Given a set of N numbers (both positive and negative) sorted in increasing order with A[i] < A[j] for all i<j, find whether there exists an index i (i = 1 .. N) such that A[i] = i. If multiple answers are present return any one of them. (desired complexity O(log n)).

     

  •  

    Give the design of an automated valet parking system with the following specifications:

     

    • There are 3 parking areas (each of different sizes) for 3 different vehicle sizes - small, medium and large.
    • Small one can accommodate only small vehicles, medium can accommodate small and medium vehicles and similarly for the large one.
    • Design a system which issues a parking ticket to a vehicle entering the lot with the optimal parking space allotted to it. For eg., if a medium vehicle arrives and both medium and large parking areas have vacant spaces, the vehicle should be allotted the medium slot.
    • Also design a syntax for the token ID which is generated when each vehicle enters the lot. The ID should be uniquely able to determine the details of the slot where the vehicle is parked for smooth parking and un-parking.
    • Provide the class design of the same.
  •  

    Virtual Onsite Round 3 (Bar Raiser, Coding + CS Fundamentals)

     

    1. Given a set of N integers find the kth largest contiguous subarray sum.
    2. Questions on OS like describe the boot up process of OS.
    3. Difference between caching, paging and buffering.
    4. Difference between stack and heap memory, calloc and malloc, etc.
    5. Things to keep in mind while designing a software product (scalability, memory leaks, deadlocks).
  •  

     

by Expert (111,270 points)
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Questions

 

Old https://leetcode.com/discuss/interview-question/488887/amazon-final-interview-questions-sde1 Amazon Final Interview Questions | SDE1 - Google Docs

 

  •  

    Number of Islands,

     

  •  

    Level Order (and Zigzag) Tree Traversal,

     

  •  

    Word Series (Word Ladder 1 & 2, Word Break 1 & 2, Word Search 1 & 2).

     

  •  

    "parking lot" OOD question

     

  •  

    Bloomberg | Software Engineering Intern | London | January 2020 [Offer] - LeetCode Discuss

     

  •  

    Amazon Dublin Ireland | Onsite - SDE New Grad 2021 | Income Calculator - LeetCode Discuss

     

  •  

    What are Design patterns? example and explanation? https://leetcode.com/discuss/interview-experience/1060893/amazon-sde-new-grad-2021-dublin-experience-offer

     

  •  

    Round2 Onsite: This was a class design. In the beginning, there were 2 LP questions then he asked how a hash table is implemented as a starter and then asked to design a file system and implement search on the filesystem based on certain parameters (like file size creation date etc)

     

    https://leetcode.com/discuss/interview-question/609070/Amazon-OOD-Design-Unix-File-Search-API

     

    Round 3: Bar raiser Basically asked LP questions and asked to Design a task scheduler (in memory) and then implement a function that finds the time a certain task takes to complete (given that there exist tasks that have to be executed before it )

     

    Round 4: Simple Number of islands question along with LP questions

     

  •  

    1 OOP questions variant of UNIX commandGame of Life Question and Iterator Question.

     

  •  

    Remove all duplicate numbers from a list.

     

  •  

    https://leetcode.com/problems/min-stack/ However, it came with the constraint that we would be needing extra O(n) space. I was also asked to implement exception handling to deal with situations when you call pop() or getMin() on an empty stack.

     

  •  

    First round: 2-3 behavioral questions followed by a coding question. The question was given a binary tree find a subtree within the binary tree that adds up to a certain target sum.

     

  •  

    Second round: 2-3 behavoral questions followed by an OOD question. The question was a bit vague and I had a hard time understanding their english but essentially it was to design a wharehouse class that had certain constraints such that the particular wharehouse could only store certain products.

     

  •  

    Fourth round: 2-3 behavioral questions. This was another coding round, which involved taking a string that say said "This sweater cost $40 dollars." The objective was to take that number and apply a 20% discount and return the string back with the updated price, i.e., "This sweater cost $32 dollars.".

     

  •  

    This round was interesting since it was not any of the Leetcode questions. I was given certain conditions for a valid transaction and I had to write a function that will determine if the transaction is valid or not. The goal of this round was to see how I can write a maintainable and scalable code. For example, how can we add more conditions for a valid transaction and still not alter the main function very much. I had LP questions as part of this round also.

     

  •  

    Find the count of a given sequence that appears in an array. There can be any amount of characters between the numbers of the sequence. ex 4,5,6,2 would have a count of 1.

     

    sequence 4,6,2

     

    array [ 3, 4, 4, 6, 7, 8 , 2, 6, 9, 2]

     

    count of sequences: 6
    https://leetcode.com/discuss/interview-question/437362/amazon-sde-count-of-sequences-within-an-array

     

  •  

    2 LP´s and Medium exercise on Trie Structure (make sure you know how to use a Trie, the Explore section here has a really good card on it). Really similar to an Amazon tagged exercise.

     

  •  

    2 LP´s, then started with an extremely simple exercise, and afterwards, the interviewer started adding complexity, to see how I adapted my solution so that it scaled. The interviewer was testing my knowledge on Object Oriented Design, which I use in my everyday work, but had not prepared for the interview. This was almost a disaster, my solution was far from good.

     

  •  

    Course Schedule II -

     

  •  

    Given huge database of sentences, write a class to find most frequently used words

     

  •  

    Questions on data structures like array list, linked list, hash table, binary search tree. Differences between these data structures and when would you use which one. Inheritance and Composition.

     

  •  

    Coding: Design a Tic Tac Toe Game

     

  •  

    Given a graph and destination D, find shortest path between all nodes. Not given any graph implementation, and input is a list of edges ([1,2,3] = Node 1 to Node 2, distance 3). Had to implement my own adjacency list and "nodes" (Dijkstra's Algorithm)

     

  •  

    Similar to this question, but exclude the combined word (ex. instead of [['car','super', 'supercar'], the answer is [['car','super'],)https://leetcode.com/discuss/interview-question/314550/amazon-onsite-interview-concatenated-words

     

  •  

    https://leetcode.com/problems/copy-list-with-random-pointer/

     

  •  

    https://leetcode.com/problems/longest-happy-prefix/

     

  •  

    https://leetcode.com/problems/insert-interval/

     

  •  

    Design a system to generate and apply coupons for e-commerce site based on product and its category.

     

  •  

    https://leetcode.com/problems/lfu-cache/

     

  •  

    Find the next value from the target node using BST

     

  •  

    https://leetcode.com/problems/string-to-integer-atoi/

     

  •  

    Longest common prefix among an array of strings - but the longest between any two (instead of the longest in all)

     

  •  

    https://leetcode.com/problems/boundary-of-binary-tree/

     

  •  

    https://leetcode.com/problems/integer-to-roman/

     

    •  

     

    K most frequent items(item_id) in a stream. Input is a stream of (item_id,timestamp).

     

    This I was able to easily solve using hashmap and min-heap

     

    Then, Interviewer asked me to find frequent items in last hour given a timestamp.

     

    For example, Given time 6:07 PM, Return k most frequent items from 5:07 PM to 6:07 PM.

     

    Gave an answer using queue, hashmap and min-heap, Not an optimal answer, But it worked.

by Expert (111,270 points)