Kotak SDE 2 interview exp
Summary
I completed three interview rounds at Kotak for an SDE 2 role: a Bar Raiser with two easy string DSA questions, a second round with a Word Ladder problem and a payment‑transaction LLD, and a final round designing an ATM system.
Full Experience
1st round Bar Raiser 90 min, mine got over in 60 min 2 dsa easy qus on string, 1.) is number palindrome & 2.) valid parentheisis using stack 1 lld (just entities, api, DB schema, and design pattern identification) no coding. 1.) that is event ticket booking system just go thru the past qus mentioned in leetcode discuss, mostly u will get the same 2nd round DSA 1hr
1.) https://leetcode.com/problems/word-ladder/description/ 2.) implement payment trascation between two users with code (it was lld problem, small part)
3rd round LLD 1hr
Design ATM Machine, end to end design (no coding, only pseudocode) ATM Machine
just sharing my asnwer, not completely correct
Flows: User goes to any physical machine Inserts the card Clicks on withdrawal amount Enter the amount Enter the PIN 1.) Amount is not sufficient/ 2.) Amount is sufficient (server) 3.) Amount is sufficient & transaction gets successful
Entity
User ATM Machine Account UserCard
User{ Id, cardID, accountId Name, Email, Address }
UserCard{ Id, Name cardNo, Start Date, End Date, CVV, PIN }
AtmMachine{ Id, amount, Loaction, WorkingStatus, no }
Account{ Id, currentBalance, accountStatus }
accountStatus{ ACTIVE, CLOSED, FROZEN }
Component Interation
WithdrwalService
USER ----> ATM MACHINE MANAGER—> 1.) CHCEK THE AMOUNT PRESENT IN THE ATM CHCEK THE AMOUNT PRESENT IN ACCOUNT -->
Extraction Card validation ( Card)--> (PIN)
Return { isAvaible }
UserAuthhentication(){
}
requestObject{ Card, Pin }
debitMethod(CARD, PIN, amount){
}
Receipt{ Id, txn }
ResponseObject{ isSuccess, AvailableBalance }
100, 500, 2000
3500
DeductBalance(int requestedAmount){ Int 3500%2000
} GenerateReceipt(){
}
API Debit of the amount—>
ATM Machine CARD READER KEYBOARD DISPLAY
DISPENSER amountAvailble with no of
Valid customer (Autherization) Debit call () locking of the money triggerReverse()
Api latency Scalability
1000 of ATM
1lakh
10 customer
10 bank
Reest id bank amount remainingAmount Date
Interview Questions (4)
Number Palindrome Check
Given an integer, determine whether it reads the same backward as forward (i.e., it is a palindrome).
Valid Parentheses (Stack)
Given a string consisting only of characters '(' and ')', determine if the string is valid. A string is valid if every opening parenthesis has a matching closing parenthesis and the pairs are properly nested.
Word Ladder
Find the length of the shortest transformation sequence from beginWord to endWord, such that only one letter can be changed at each step and each intermediate word must exist in the given word list.
Design ATM Machine
Design an end‑to‑end ATM system covering user flow, entities, APIs, and scalability considerations.
Preparation Tips
I prepared by reviewing past questions on LeetCode Discuss and focusing on common DSA and system‑design topics.