E-Ring Software Developer Intern Interview Questions and Answers

3 questions of medium to hard coding questions.

Q1. Technical interview including SQL, one programming language, and dbms based questions. the interview went well and was of 90mins.
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Round duration - 60 Minutes
Round difficulty - Easy

Asked every question possible from resume

Q1. 
Merge Sort Problem Statement
You are given a sequence of numbers, ARR. Your task is to return a sorted sequence of ARR in non-descending order using the Merge Sort algorithm.
Explanation:
The Merge Sort...read more
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Q2. 
Cycle Detection in a Singly Linked List
Determine if a given singly linked list of integers forms a cycle or not.
A cycle in a linked list occurs when a node's next points back to a previous node in the ...read more
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. Can you explain the low-level design of an e-commerce website?
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Round duration - 90 minutes
Round difficulty - Medium

It consist three question - first que is of related to tree and i gave difficulty level of this question as hard. second que is of based on logical and reasoning , it is medium level question and third que can be done by map and it is also medium level que.
In codility platform we are not able to see hidden test cases whether it is satisfied or not . we just have to submit after passing sample testcases.

Q1. 
Minimum Number of Swaps to Sort an Array
Find the minimum number of swaps required to sort a given array of distinct elements in ascending order.
Input:
T (number of test cases)
For each test case:
N (siz...read more
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Q2. 
Maximum Non-Adjacent Subsequence Sum
Given an array of integers, determine the maximum sum of a subsequence without choosing adjacent elements in the original array.
Input:
The first line consists of an...read more
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Q3. 
Left View of a Binary Tree Problem Statement
Given a binary tree, your task is to print the left view of the tree.
Example:
Input:
The input will be in level order form, with node values separated by a...read more
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Round duration - 30 minutes
Round difficulty - Medium

basically this round is just same as HR round . they asked me behavioural questions and about my projects , hackathon. the timing is mid noon and interviewer is supportive , it makes first comfortable then start questioning . for this round i suggest be honest , don't just express your qualities but trying to show them by your skills and work.

DSA algorithms array linkedlist strings dp

Q1. Merge 2 sorted linked list
Ans. 
Merge 2 sorted linked lists into a single sorted linked list
• Create a new linked list to store the merged result

• Compare the values of the nodes from both lists and add the smaller one to the result list

• Move the pointer of the list with the smaller value to the next node and repeat until both lists are empty
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Round duration - 100 minutes
Round difficulty - Medium

Test started at 04:00 PM sharp and complete the same by 06:00 PM.
The test duration is 100 minutes.
Environment (Amcat) is user friendly and understandable.
Web cam and microphone were also enabled.

Q1. 
Longest Substring with At Most K Distinct Characters
Given a string S of length N and an integer K, find the length of the longest substring that contains at most K distinct characters.
Input:
The first...read more
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Q2. 
Find the Duplicate Number Problem Statement
Given an integer array 'ARR' of size 'N' containing numbers from 0 to (N - 2). Each number appears at least once, and there is one number that appears twice. Yo...read more
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Round duration - 40 minutes
Round difficulty - Hard

This round was conducted on skype platform. I was shared the invitation link one day prior to the interview and also was told the name of my interviewer. I looked at the profile of the interviewer at linked.in and got a better understanding of what kind of person he was and prepared accordingly. The round was scheduled at 3 :00 pm on 5th Nov and I was eagerly waiting for the clock hands to reach 3 o'clock since morning and finally I went in front of him after wearing a white shirt and a black coat over it along with a tie over it.

Q1. 
Ninja and Binary String Problem Statement
Ninja has a binary string S of size N given by his friend. The task is to determine if it's possible to sort the binary string S in decreasing order by removing a...read more
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Q2. 
Split the String Problem Statement
You are given a string str consisting of N lowercase alphabets. Your task is to determine if it is possible to divide the string into three non-empty substrings such tha...read more
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Round duration - 40 minutes
Round difficulty - Easy

This round was scheduled on 15th Nov, almost after 10 days of the previous technical round. I got the confirmation of passing the previous round on 11th Nov and was asked to appear in this final round which was scheduled on 15th Nov at 11:00 am in the morning and it was going to be an HR round which probably was my favourite among all the other rounds. I prepared for by reading interview experiences available at coding ninjas and geeksforgeeks.

Round duration - 120 minutes
Round difficulty - Easy

It consisted of 3 coding questions which were purely based on Data Structures and Algorithms.

Question 1 - Find the length of the longest switching sub-array. An array is called switching if all numbers in even positions are equal and all numbers in odd positions are equal. 


Question 2 - It was a long passage question on Dynamic Programming but the solution was really easy.

Question 3 - Given a string S consisting of N lowercase letters, return the minimum number of letters that must be deleted to obtain a word in which every letter occurs a unique number of times. Ex - "aaaabbbb" should return 1, as when we delete 1 a or 1 b , a and b will have different frequencies.


The major point to note in the coding round was that they did not have any time or space limit, so brute force solutions were also accepted. 
The result of my test was declared just as the test ended and I scored a 100%, but they took a long time to release the final shortlist. There was a gap of about a week between the test and interviews.

Q1. 
Longest Switching Subarray Problem Statement
Determine the length of the longest contiguous subarray in a given array of positive integers, where the subarray qualifies as 'switching'. An array is defined...read more
Ans. 
It's like a sliding window problem.
We keep track of even and odd equality with 2 variables, even and odd.
Whenever we come across a unmet condition, like index even but not equal with even variable and same goes for odd, we first
Record the length till now in max_len.
Reset start to i-1 as this is need incase of all elements equal.
Reset even and odd according to current index i to arr[i] and arr[i-1] respectively.
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Q2. 
Unique Frequency Problem Statement
Given a string 'STR' with lowercase letters, determine the minimum number of deletions required to ensure that every letter in the string appears a unique number of time...read more
Ans. Brute Force
As we are only allowed to delete the character, thus the resulting string after deletion of some character would be the subsequence of the string. So, we have to find such a subsequence which has the unique frequency of each character. 
 
Initialise a variable ‘ans’ that will store the minimum number of characters that are needed to remove from the string. Create all the subsequences of the string an...read more
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Round duration - 40 minutes
Round difficulty - Easy

Amex came for two profiles - Tech Role and Analyst, 19 and 23 people respectively were shortlisted for the interviews. Fortunately, I was shortlisted for both the roles. I was asked basic question of C++ and it was majorly an HR Round

Round duration - 20 minutes
Round difficulty - Easy

It was a fairly simple round conssting of 5 - 6 questions related to coding, puzzles and me.

What are your interests? 
What projects have you done and your field of interest?

Round duration - 50 minutes
Round difficulty - Easy

This round was purely technical
No introduction was done, straight to the point

My preference was the Tech Role, so as I was selected in this, I never had to give interviews for the Analyst role. In total 5 people were selected in the Analyst profile and 4 in the Tech profile.

In the end, I was offered a 6 months internship at Amex.

Q1. 
Palindrome Linked List Detection
Given a singly linked list of integers, determine if it is a palindrome. A linked list is considered a palindrome if it reads the same forward and backward.
Example:
Inp...read more
Ans. 
I gave the two pointer approach. Then he said what if we are provided with the length of the list. I said that we will move forward in the list till n/2 nodes and then the same approach as above. Then he said what if we had to do it with a stack. I said we will add elements into the stack till n/2 nodes and then start popping elements while simultaneously traversing the linked list from the (n/2+1)th node till n if the...read more
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