R1: PSDS

• Q1. given a string, sort it according to the frequency of characters from heighest to lowest
  • Eg: tree → eert or eetr both are valid
  • Eg: Aacc → ccAa or ccaA both are valid
  • Approcah 1: count frequency of all chars and sort them according to fre and then creat string: TC: O(n+ mlogm), m= distinct chars
  • Approach 2: store freq of all chars and traverse multiple times picking one having max fre. TC: O(n+ m*m)
  • Approach 3: put all chars fre in max heap. TC: O(n + mlogm)
    • Implemented this
  • He was saying can you avoid sorting, I couldnot come up with best approach also my code didnot ran in 1st run due to wrongly writting pair as Pair in c++
  • Approach 4: bucket sort. But this also has TC of: O(n + max(m, max freq of char). I think he wanted this approach
• Q2. Tell whether a binary tree is heap or not
  • I gave him the 2 conditions to tell, he asked have I ever seen this question before? I said yes. Then he said I will give you another question
• Q3. Tell whether a tic tac toe board is a valid one?
  • In requirements I didn’t asked which player will turn first and this he pointed out later
  • coded in c++, a lot of struggle with parsing the input
• At last he asked if I have any questions
• There was a constraint of time on the interviewer which he was clearly telling to do this question in next 30-35mins so we can go to another one
• R2: Java PS
  • He took me to some hackrrank code pair
  • Q1. Next permutation
    • I enacted as if I have come up with solution there only and seeing this question first time, telling him each and every approach
    • He asked me to optimize how I search a number GT given number in descending arr
    • Then he didn’t asked to code next permutation ques
  • Q2. Implement binary search to find number GT a given number on an arr
    • Then ask to write edge cases for it
  • Q3. Number of ways to reach nth stair given I can take 1.2….k steps at a time
    • such a simple ques, I did a big mistake. fn(n) = SUM(fn(n-i)+1) where i= [1,2,..k] and n-i≥0
    • He couldnot understand my function, I explained him multiple times
    • Then he asked to give an example, I explained and then he pointed out mistake that we need not to add +1
    • I wrote base condition of recursions, told how it can be efficiently solved using DP
    • He didn’t asked me to code, although I said I can code in 1 min
  • Q4. About most difficult problem/project I have worked upon
    • I explained it was an algorthim challenging problem, he couldnot asked any question from it, just understood the business
    • then he said was it monolithic or microservices. How microservices used to interact
    • Difference between asyn and sync operations and when to use them
      • I explained giving a bussiness example of prev org transaction/payout process
  • Q5. what is difference between REST and normal API?
    • I explained that REST apis are stateless
    • He asked more, then I couldnot
  • Q6. difference between PUT and PATCH on and explain on basis of input parameters?
    • I couldnot explain satisfactorily
  • Atlast do you have any questions for me, I can answer only 1 question
    • I asked 3 ques and showed my enthusiasm

R3: LLD

• Design Cache system supporting get and put operation and configurable eviction strategy. Initially assume it is LRU eviction strategy
• My initial system was tightly coupled with LRU
• Later he told this strategy can be different also
  • Then optimized it
• One very big mistake I was doing again and again was, I was de
• signing the classes attributes on the fly according to the usage and thus interviewer had to correct me again and again, when he point I quickly gave the reason why it will not work and then improve it. Bad impact.
• I was jumping more into writing the algo rather then first structuring the classes. Bad impact.

R4: HM

• Asked how the Adobe process looks

• Project and prev work

  • Migration:
    • How much related the data was in DynamoDB
    • Why you moved from DynamoDB to PG?
      • I said it was cost reason, he said if scale is not there then what is the point of cost? I said it was decided by management and also we were querying on the DB
  • Schema of product
  • What are new new things you are expecting?
    • scale
    • more specific requirements

  Q. Design:

  /*
  currency values
  1 Dollar -> 80 Rs
  1 Dhiram -> 35 Rs
  .
  .
  .
  .
  .
  
  1 Dollar -> 81 Rs
  
  - What is the value for 1 currency to another
  Dollar, Dhiram, USD  -> Rupees
  
  (125 Dollar) -> 125
  
  - can also asked in the past or current
  */
  
  Money
      - float amount
      - CurrencyEnum currency
  
  CurrencyEnum
  - Dollar
  - Dhiram
  - Rupees
  
  GET public Money convert(Money input, Timestamp time){
      if(time==null){
          time = System.time;
      }
      ...
      ...
      ...
      ...
      ...
  }
  
  POST public bool createConversion(CurrencyEnum fromCurrency, 
  float conversionFactor){
      ...
  }
  Map<String, Vector<pair<cf, time>>
  
  HashMap -> currency -> (timstamp, conversionFactor)
      Dollar-> (75 T1), (76 T2), (75, T3)
      
      Dhiram 35 T3
  
  • In this he corrected me couple of times about the the inputs I am taking
    • I felt I was little slow in telling
  • How many types on indexing PG supports?
    • He wanted B, B+ tree type answer
  • What are my expectations from the role?
  • Are those things am I not getting in the current role?
  • AMA