DBS Bank Java Microservice Developer Interview Questions and Answers

Round duration - 150 minutes
Round difficulty - Medium

For MCQ Round, we have 2 rounds:- 
1. Logical Reasoning (Window of 4 hours)
2. Mathematical Reasoning(Window of 4 hours)
The environment was fine. They gave an option of attempting a mock test in order to familiarize us with the environment

Logical Reasoning, in which there were 12 questions, and for each question we had a time limit of 75 seconds. There was a cut-off of 40 for the next round, and people who qualified were sent an e-mail with a link to continue with the process.

Numerical Reasoning, in my opinion, was the most challenging round. The questions were in a pair of 3 in which a table/bank statement was given and 3 questions were based on that. The questions were purely based on calculations and semi-subjective. The time given for the 1st question was 90 seconds and for the rest 2 questions, 75 seconds each

For Coding Round, 
120 minutes window(Test was of 90 minutes)
We have two questions
For the first question(30 Minutes)
For the second question(60 Minutes)
The tricky thing was we only had one attempt, i.e we were allowed to submit the solution only once.

Q1. 
Maximum Frequency Number Problem Statement
Given an array of integers with numbers in random order, write a program to find and return the number which appears the most frequently in the array.
If multip...read more
Ans. 
Find the number with the highest frequency in an array, returning the first one in case of ties.
• Count Frequencies: Use a hash map to count occurrences of each number in the array.

• Track First Occurrence: Store the index of the first occurrence of each number to resolve ties.

• Iterate Efficiently: Loop through the array once to build the frequency map and another pass to determine the maximum frequency.

• Example: For input [...read more
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Q2. 
Mike and Mobile Problem Statement
Mike, a little boy who loves solving math problems, was playing with his mom's mobile phone. The mobile keypad includes 12 buttons: 10 digit buttons (0-9) and 2 non-digit...read more
Ans. 
Mike can generate unique numbers by pressing mobile keypad buttons, following specific rules for adjacent presses.
• Button Press Rules: Mike can press the same button or an adjacent one after the initial press.

• Initial Choices: For N=1, he can choose any of the 10 digits (0-9), resulting in 10 unique numbers.

• Adjacent Button Logic: For N=2, starting from any digit, he can press the same or adjacent digits, leading to 36 co...read more
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Round duration - 40 minutes
Round difficulty - Medium

The timing was around 1 pm and the whole interview went for about 40 minutes.
The interviewer first went through my resume and asked me to introduce myself. After my introduction, he asked me about my projects mentioned in the resume. In the introduction itself, I told him that I am interested in competitive programming and preparing for ICPC. He then asked me about my preparation for ICPC. He then asked me some questions from OOPS. I was then asked 1 simple CP problem. The interviewer also asked about situation-based problems. As I previously mentioned about Competitive Programming, he asked how this will help in adding value to the company.

Q1. 
Remove Duplicates Problem Statement
You are given an array of integers. The task is to remove all duplicate elements and return the array while maintaining the order in which the elements were provided.
...read more
Ans. 
The task is to remove duplicates from an array while preserving the original order of elements.
• Use a set to track seen elements and a list to store the result, ensuring duplicates are skipped.

• Example: For input [1, 2, 2, 3, 1], the output should be [1, 2, 3].

• Iterate through the array, adding elements to the result list only if they haven't been seen before.

• This approach maintains the order of first occurrences of each ...read more
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Round duration - 10 minutes
Round difficulty - Easy

In this round interviewer basically asked about my project in detail and also asked about various technologies used in that project.

Round duration - 10 minutes
Round difficulty - Easy

We were asked about family background, location of the intern, any interest in startups (as they don’t want students who they hire also work with startups side by side), etc.

Round duration - 90 Minutes
Round difficulty - Medium

Coding round was conducted in the morning for 1.5 hours from 10:00 am to 11:30 am. Exam was conducted on HACKEREARTH which is a user-friendly platform with various edge test-cases. Since exam was done through online mode due to COVID-19, therefore camera was on for invigilation. A well working camera and microphone were needed for successful completion of exam.

Q1. 
Words Magic with Prefix Replacement Problem
Ninja is provided with a dictionary of words, WORDS, and a sentence, SENTENCE, which consists of words separated by spaces. The goal is to minimize the size of ...read more
Ans. 
The goal is to minimize the size of a sentence by replacing words with prefixes from a given dictionary.
• Iterate through each word in the sentence and check if a prefix exists in the dictionary

• Replace the word with the smallest prefix found in the dictionary

• Repeat the process for all words in the sentence
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Round duration - 90 minutes
Round difficulty - Easy

Q1. 
Occurrence of Each Word: Problem Statement
You are given a string S consisting of several words. Your task is to count the number of times each word appears in string S. A word is defined as a sequence of...read more
Ans. 
Count the occurrence of each word in a given string.
• Split the string into words using spaces as delimiters.

• Use a hashmap to store the count of each word.

• Iterate through the words and update the count in the hashmap.

• Output each unique word with its occurrence count.
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Round duration - 30 minutes
Round difficulty - Easy

Q1. 
Anagram Pairs Verification Problem
Your task is to determine if two given strings are anagrams of each other. Two strings are considered anagrams if you can rearrange the letters of one string to form the...read more
Ans. 
Check if two strings are anagrams of each other by comparing their sorted characters.
• Sort the characters of both strings and compare them.

• Use a dictionary to count the frequency of characters in each string and compare the dictionaries.

• Ensure both strings have the same length before proceeding with comparison.

• Handle edge cases like empty strings or strings with different lengths.
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Round duration - 45 minutes
Round difficulty - Medium

Q1. 
Palindromic Substrings Problem Statement
Find the total number of palindromic substrings in a given string STR.
Example:
Input:
"abbc"
Output:
5
Explanation:
The palindromic substrings are: ["a", "...read more
Ans. 
Count the total number of palindromic substrings in a given string.
• Iterate through each character in the string and expand around it to find palindromic substrings.

• Use dynamic programming to store previously calculated palindromic substrings.

• Consider both odd and even length palindromes while counting.

• Example: For input 'abbc', palindromic substrings are ['a', 'b', 'b', 'c', 'bb']. Total count is 5.
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Q2. How can you find the 4th highest salary from a table in a database?
Ans. 
To find the 4th highest salary from a table in a database, you can use a SQL query with the ORDER BY and LIMIT clauses.
• Write a SQL query to select distinct salaries from the table in descending order.

• Use the LIMIT clause to retrieve the 4th row from the sorted list.

• The query would look like: SELECT DISTINCT salary FROM table_name ORDER BY salary DESC LIMIT 3, 1
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Round duration - 90 minutes
Round difficulty - Medium

It was an online test round of 90 minutes orgainsed in Hackerearth platform. It consists of 15 mcq questions and 2 coding questions. The level was moderate. Timing of test was in morning and platform was quite good.

Q1. 
Shopping Spree Problem Statement
Preeti plans to shop for her father's birthday at a store with unlimited quantities of N different items. She has a budget that allows her to buy a maximum of K items. Hel...read more
Ans. 
Calculate the number of ways Preeti can purchase items within budget, with at least one item quantity differing.
• Use dynamic programming to calculate the number of ways to purchase items within budget.

• Consider different scenarios where Preeti buys different quantities of each item.

• Return the result modulo 10^9 + 7 to handle large answers.
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Round duration - 50 minutes
Round difficulty - Medium