ACKO Software Developer Intern Interview Questions, Process, and Tips

4 coding problems + 1 sql problem

Q1. Gas Station Problem On leetcode
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Q2. Simple Tree Traversal Problem LC medium
Ans. 
Given a binary tree, return the inorder traversal of its nodes' values.
• Inorder traversal: left subtree, root, right subtree

• Use recursion to traverse the tree

• Implement a stack-based iterative solution for better space complexity
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Round duration - 90 minutes
Round difficulty - Easy

The online round had 2 coding questions and one question of a regular expression.

Q1. 
Find All Pairs Adding Up to Target
Given an array of integers ARR of length N and an integer Target, your task is to return all pairs of elements such that they add up to the Target.
Input:
The first line ...read more
Ans. 
Find all pairs of elements in an array that add up to a given target.
• Iterate through the array and for each element, check if the complement (target - current element) exists in a hash set.

• If the complement exists, add the pair to the result. If not, add the current element to the hash set.

• Handle cases where the same element is used twice in a pair (e.g., target = 6, array = [3, 3]).
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Q2. 
Increasing Subsegment Problem Statement
Given a sequence ARR consisting of N integers, your task is to identify the longest subsegment of ARR, where you can change at most one number to make the subsegmen...read more
Ans. 
Find the longest subsegment where at most one number can be changed to make it strictly increasing.
• Iterate through the array and keep track of the longest increasing subsegment with at most one change.

• If a number violates the increasing order, try changing it and check if the subsegment becomes strictly increasing.

• Update the length of the longest subsegment found so far.

• Return the length of the longest subsegment for e
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Round duration - 60 minutes
Round difficulty - Easy

First 10 minutes started with the Introduction. Then he asked about my projects. He seemed interested in my projects and asked a lot of questions about them. He asked questions related to Node Js, React Js, Mongo DB, AWS as all these were mentioned in my Resume. Around 25 minutes was completed explaining each and everything.

Then he started with the coding questions. I was allowed to share my screen and use any of my favourite text editors. I chose ‘VS Code’.

I was able to solve 2 coding questions very easily. I got stuck in the puzzle as I didn’t solve any puzzles before. I was able to come up with different approaches, but they weren’t the most optimal. He tried giving me a lot of hints but still wasn’t able to solve it. I had a positive can-do attitude throughout, and I was really close to solving it.

Feedback: He told me I performed well and asked if I had any questions for him. I asked for the solution to the puzzle. He explained to me the solution and I told him that I will practice puzzles.

Around 5-6 students got selected for 2nd Interview.

Q1. 
Move Zeros To Left
You are provided an array ARR of integers. Your task is to rearrange this array such that all elements with zero values are moved to the left, and all non-zero elements follow them, pre...read more
Ans. 
Rearrange array with zeros on the left and non-zeros on the right while maintaining original order.
• Iterate through the array from right to left, moving non-zero elements to the end of the array.

• Track the index where non-zero elements should be placed.

• Fill the beginning of the array with zeros and the rest with non-zero elements in their original order.
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Q2. 
Maximum Sum of Disjoint Pairs with Specific Difference
Given an array of integers and a number K, your task is to form pairs of elements from the array such that the absolute difference between them is st...read more
Ans. 
Find maximum sum of disjoint pairs with specific difference in an array.
• Sort the array in non-decreasing order.

• Iterate through the array and form pairs with absolute difference less than K.

• Keep track of the sum of disjoint pairs to maximize it.

• Return the maximum sum obtained.
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Round duration - 35 minutes
Round difficulty - Medium

It started with a brief Introduction and in-depth discussions on projects. He also asked me a lot of questions about my previous internship. He asked me some behavioural questions as well.

I was able to solve the question, and he did not ask me any other questions. This round was really short for me and was finished in around 35 minutes, well before time. I asked about my feedback, and he told me that the ‘HR’ will get back to me. I thought he was not satisfied with my answers and I will be rejected though I gave very good answers to every question.

3 students got selected for the next round. I think he was satisfied and did not want to waste more time asking questions.

Q1. 
Polynomial Simplification Problem Statement
You are provided with two arrays representing the coefficients and degrees of a polynomial expression. Your task is to simplify this polynomial into its general...read more
Ans. 
Simplify a polynomial expression by combining like terms and arranging them in descending order of degrees.
• Iterate through the coefficients and degrees arrays to combine like terms

• Create a new array to store the simplified polynomial in descending order of degrees

• Return the simplified polynomial array
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Round duration - 60 minutes
Round difficulty - Medium

It started with an introduction and discussion on projects. He seemed very curious about my project and went ahead to cross-question every functionality. We discussed everything and how the code works. He asked me a lot of questions on ‘Socket’ as my project mentioned it.

HR-related questions such as:
Why do you want to join the company?
Where do you see yourself in the next 5 years?
What are your strengths and weakness?

Round duration - 50 minutes
Round difficulty - Easy

Q1. 
Move Zeros to Left Problem Statement
Your task is to rearrange a given array ARR such that all zero elements appear at the beginning, followed by non-zero elements, while maintaining the relative order of...read more
Ans. 
Rearrange an array such that all zero elements appear at the beginning, followed by non-zero elements, maintaining relative order of non-zero elements.
• Iterate through the array and move all zero elements to the left side of the array while maintaining the relative order of non-zero elements.

• Use two pointers approach to swap elements efficiently.

• Ensure to solve the problem in linear time and constant space complexity.

• Ex...read more
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Q2. 
Rat in a Maze Problem Statement
Given a maze of size N * N with a rat placed at the top-left corner, find and print all possible paths that the rat can take to reach the bottom-right corner. The rat can m...read more
Ans. 
Find and print all possible paths for a rat to reach the bottom-right corner of a maze.
• Create a recursive function to explore all possible paths in the maze.

• Keep track of the current path and mark visited cells.

• Return the paths as matrices with 1 for cells in the path and 0 for others.
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Round duration - 60 minutes
Round difficulty - Medium

First 10 minutes started with the Introduction. Then he asked about my projects. He seemed interested in my projects and asked a lot of questions about them.

Q1. 
Matrix Chain Multiplication Problem Statement
You are provided with a chain of matrices A1, A2, A3, ..., An. The goal is to determine the minimum number of scalar multiplications needed to multiply these ...read more
Ans. 
The goal is to determine the minimum number of scalar multiplications needed to multiply a chain of matrices together.
• Understand the matrix chain multiplication problem statement and how the dimensions of matrices are defined by the input array.

• Implement a dynamic programming approach to find the minimum cost of matrix multiplication.

• Consider the constraints provided and optimize the solution accordingly.

• Test the solut...read more
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Q2. How would you design an application like Instagram?
Ans. 
Designing an application like Instagram involves creating a platform for sharing photos and videos with social networking features.
• Implement user profiles with the ability to upload, like, comment, and share photos/videos

• Develop a news feed algorithm to display content based on user preferences and interactions

• Include features like filters, hashtags, geotagging, and direct messaging

• Integrate push notifications for like...read more
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Round duration - 20 minutes
Round difficulty - Easy

Round duration - 30 minutes
Round difficulty - Easy

Q1. 
Delete a Node from a Linked List
You are provided with a linked list of integers. Your task is to implement a function that deletes a node located at a specified position 'POS'.
Input:
The first line co...read more
Ans. 
Implement a function to delete a node from a linked list at a specified position.
• Traverse the linked list to find the node at the specified position.

• Update the pointers of the previous and next nodes to skip the node to be deleted.

• Handle cases where the position is at the beginning or end of the linked list.

• Ensure to free the memory of the deleted node to avoid memory leaks.
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Round duration - 120 minutes
Round difficulty - Easy

Q1. 
Binary Tree Diameter Problem Statement
You are given a Binary Tree, and you need to determine the length of the diameter of the tree.
The diameter of a binary tree is the length of the longest path betwe...read more
Ans. 
The problem involves finding the diameter of a binary tree, which is the length of the longest path between any two end nodes in the tree.
• Traverse the tree to find the longest path between two nodes.

• Use recursion to calculate the diameter of the binary tree.

• Keep track of the maximum diameter found during traversal.

• Consider the height of the left and right subtrees to calculate the diameter.

• Example: For the input 1 2 3 ...read more
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