Soho House Mumbai Senior ETL Developer Interview Questions and Answers for Experienced

Round duration - 90 minutes
Round difficulty - Medium

Q1. Rotate Matrix right by K times
You have been given a matrix ‘MAT’ of size 'N' * 'M' (where 'N' and 'M' denote the number of rows and columns respectively) and a positive int...read more
Ans. Row-wise rotation
This approach is based on the fact that when we rotate an array to the right by ‘K’ times, it shifts ‘K’ elements from the end to the beginning of the array while the remaining elements shift towards the end. The effective rotations in ‘MAT’ can be from 0 to 'M' - 1, as we get the same matrix ‘MAT’ after every 'M' rotations. So, we will set ‘K’ to ‘K’ % ‘M’.
 
Now, we traverse ‘MAT’ row-wise. We wil...read more
Answered by CodingNinjas
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Q2. Word Search
You are given a two-dimensional grid having 'N' rows and 'M' columns, consisting of upper case characters. You are also given a word 'WORD'. You have to find the number...read more
Ans. 
1. Coded using recursion and backtracking but the time complexity was of exponential order so time limit exceeded.
2. Tried to code it using DFS but couldn't code it in the given time.
Answered by CodingNinjas
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Round duration - 75 minutes
Round difficulty - Medium

Interview started with an introduction and walk through the resume for first 5 minutes. After that, interview asked few coding questions.

Q1. Largest Island
You have been given a non-empty grid consisting of only 0s and 1s. You have to find the maximum area of an island in the given grid.
An island is a group of 1s (representing land) connecte...read more
Ans. 
1. I was little stuck in stuck in start but later on came up with DFS approach.
2. Interviewer was satisfied the approach and asked me to code it.
Answered by CodingNinjas
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Q2. Given a 2D matrix having 0s and 1s, each row is sorted. Find the row having the maximum number of consecutive ones in the matrix.
Ans. 
1. Told the brute force which is to traverse the whole matrix.
2. Optimized it using binary search on each row. But interviewer want more optimized approach than this.
3. After thinking for few minutes, came up with the approach of starting from top right and take decision whether to go left or down depending on the element in left. Interviewer asked me to further optimize.
4. Optimized it by using combination of 3rd appr...read more
Answered by CodingNinjas
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Q3. Pythagorean Triplet
You are given an array of n integers (a1, a2,....,an), you need to find if the array contains a pythagorean triplet or not.
An array is said to have a pythagorean triplet if there exi...read more
Ans. Brute Force
• One simple naive solution is to try every possible triplet present in the array as a candidate for the pythagorean triplet.
• So, we simply run three nested loops, and pick three integers and check if they follow the property given in the problem statement( i.e for three integers a,b and c a^2 b^2 = c^2).
• If we find any required triplet, we return true. Otherwise, if we can't find any valid triplet, we return fa...read more
Answered by CodingNinjas
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Q4. Top View of Binary Tree
You are given a Binary Tree of integers. You are supposed to return the top view of the given binary tree. The Top view of the binary tree is the set of nodes that are visible when ...read more
Ans. Using Pre-Order Traversal
As we know that all three traversals, i.e. pre-order, in-order and post-order, visit the tree node at once. We can use any of them. Here we are going to use pre-order traversal for the explanation. So while traversing in the pre-order traversal, we will keep track of horizontal distance of the node which is going to be visited from the root node, and we also keep track of the vertical level of ...read more
Answered by CodingNinjas
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Round duration - 90 minutes
Round difficulty - Medium

This round was focused on DSA along with short discussion on computer science fundamentals. For coding problems, I was asked to code the first problem only. For others, had to discuss the approach only. For computer science fundamentals, discussion on OOPS. Differences between process and threads were discussed.

Q1. Fix BST
Given a Binary Search Tree, where exactly two nodes of the same tree were swapped by mistake. The task is to restore or fix the BST, without changing its structure.
A binary search tree (BST), al...read more
Ans. 
After getting some of the hints, was able to come up with in-order traversal approach which takes extra space. Interviewer wanted better approach without extra space. But couldn't think of it.
Answered by CodingNinjas
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Q2. Implement Stack with Linked List
You need to implement the Stack data structure using a Singly Linked List.
Create a class named 'Stack' which supports the following operations(all in O(1) time):
...read more
Ans. Best Approach
1. Maintain a linked list. Keep track of its head, and size at all times, and update them accordingly whenever a new operation is performed.
2. Following is the way we can implement all functions of the stack using linked list:
   1. First, initialize a head node, and the size of the list as NULL and 0 respectively.
   2. Then for push function, insert new elements at the head of the list, i.e. the new element will become the ...read more
Answered by CodingNinjas
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Q3. Given N documents and a set of keywords was given, you have to retrieve document having highest frequency of those keywords first and then others.
Ans. 
1. Told the approach using hashmap.
2. Optimized it further by using tries.
Answered by CodingNinjas
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