Ninjacart Software Developer Intern Interview Questions and Answers for Freshers

Round duration - 24 hours
Round difficulty - Medium

Round duration - 120 Minutes
Round difficulty - Medium

It was a Data Structures and Algorithm Round and Discussion on My assignment round to check my Problem Solving Skills.
And the Interviewer was very friendly to me. I first introduced myself to the interviewer and what did I have done in past as a Software Engineer and Why I want to work in Grofers.
 

Q1. 
Top View of Binary Tree
Given a binary tree of integers, the task is to return the top view of the given binary tree. The top view of the binary tree is the set of nodes visible when viewed from the top.
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Ans. 
Return the top view of a binary tree given in level-order format.
• Traverse the binary tree in level-order and keep track of the horizontal distance of each node from the root.

• Use a map to store the nodes at each horizontal distance, and return the nodes at the top view.

• Handle null nodes by adjusting the horizontal distance accordingly.

• Example: For the given binary tree, the top view will be {10, 4, 2, 1, 3, 6}.
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Q2. 
Maximum Possible Time Problem Statement
Given an array ARR consisting of exactly four integer digits, your task is to form the maximum possible valid time in a 24-hour format using those digits.
Explanat...read more
Ans. 
Given an array of four digits, form the maximum valid 24-hour time. Return -1 if not possible.
• Iterate through all permutations of the digits to find the maximum valid time.

• Check if the time is valid (between 00:00 and 23:59) before returning.

• Handle cases where no valid time can be generated by returning -1.
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Round duration - 150 minutes
Round difficulty - Medium

The interview was scheduled at 6 pm and the duration of the interview was 1.5 hrs but went for around 2.5 hrs. The interviewer started with a brief intro about me. Asked me some coding questions. After coding questions he started asking questions on dbms like difference between sql and no sql, what is horizontal and vertical scaling and when we use them. Then some questions on computer networks like how web browsers works, different between http and HTTPS, what is TCP. After this he asked about my projects and the technology I worked on during the intern.

Q1. 
Snake and Ladder Problem Statement
Given a Snake and Ladder Board with 'N' rows and 'N' columns filled with numbers from 1 to N*N starting from the bottom left of the board, and alternating direction each...read more
Ans. 
Find the minimum number of dice throws required to reach the last cell on a Snake and Ladder board.
• Use Breadth First Search (BFS) algorithm to find the shortest path on the board.

• Create a mapping of each cell to its next possible moves based on dice outcomes.

• Consider the snakes and ladders on the board while calculating the next possible moves.

• Track the number of dice throws needed to reach each cell and update it as y...read more
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Q2. 
Deletion In Doubly Linked List
You are given a Doubly Linked List with 'N' positive integers. Your task is to delete a node at a given position 'POS' in this linked list.
Input:
The first line of input ...read more
Ans. 
Implement a function to delete a node at a given position in a Doubly Linked List.
• Traverse to the node at the specified position in the Doubly Linked List.

• Adjust the pointers of the previous and next nodes to remove the node at the specified position.

• Update the pointers accordingly to maintain the integrity of the Doubly Linked List.

• Handle edge cases such as deleting the head or tail node.

• Ensure to free the memory of t
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Round duration - 20 minutes
Round difficulty - Easy

Round duration - 60 Minutes
Round difficulty - Easy

The overall interview experience was quite smooth and the interviewers were very kind.
I was asked 2 coding questions.

Q1. 
Reverse Doubly Linked List in Groups Problem
You are provided with a Doubly Linked List consisting of integers and a positive integer 'K', which represents the size of the group. Your task is to modify th...read more
Ans. 
Reverse groups of K nodes in a doubly linked list
• Iterate through the linked list in groups of size K

• Reverse each group of nodes

• Handle cases where the number of remaining nodes is less than K
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Q2. 
Largest Rectangle in Histogram Problem Statement
You are given an array/list HEIGHTS of length N, where each element represents the height of a histogram bar. The width of each bar is considered to be 1.
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Ans. 
Calculate the area of the largest rectangle that can be formed within the bounds of a given histogram.
• Iterate through the histogram bars and maintain a stack to keep track of increasing heights.

• Calculate the area of the rectangle formed by each bar as the smallest height in the stack multiplied by the width.

• Update the maximum area found so far and return it as the result.
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Round duration - 50 Minutes
Round difficulty - Medium

3 coding questions were asked and 1 on system design.

Q1. 
Maximize the Sum Through Two Arrays
You are given two sorted arrays of distinct integers, ARR1 and ARR2. If there is a common element in both arrays, you can switch from one array to the other.
Your task...read more
Ans. 
Given two sorted arrays, find the path through common elements for maximum sum.
• Start with the array containing the smaller first common element

• Switch arrays at common elements to maximize the sum

• Continue adding elements until the end of the arrays
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Q2. 
Number of Islands Problem Statement
You are provided with a 2-dimensional matrix having N rows and M columns, containing only 1s (land) and 0s (water). Your goal is to determine the number of islands in t...read more
Ans. 
Count the number of islands in a 2D matrix of 1s and 0s.
• Use Depth First Search (DFS) or Breadth First Search (BFS) to traverse the matrix and identify connected groups of 1s.

• Maintain a visited array to keep track of visited cells to avoid redundant traversal.

• Increment the island count each time a new island is encountered.

• Consider all eight possible directions for connectivity between cells.

• Handle edge cases such as bo...read more
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Q3. How would you design Instagram?
Ans. 
Designing Instagram involves creating a user-friendly platform for sharing photos and videos with social networking features.
• Focus on a clean and intuitive user interface for easy navigation

• Implement features like photo filters, stories, direct messaging, and explore page

• Incorporate algorithms for personalized content recommendations

• Ensure robust security measures for user data protection

• Integrate advertising options f...read more
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Round duration - 15 Minutes
Round difficulty - Medium

3 questions easy-medium level leetcode problem I solved 2 completely and 3rd question partially (9/15 test cases passed) to move on to 2nd round

Q1. Implement an app similar to splitwise
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Lists and Trees were asked

Longest substring without repetition

Q1. 2 DSA question medium leetcode
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Q1. 1 Dsa question and about projects
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