Altera Digital Health Software Developer Intern Interview Questions and Answers

Round duration - 7 days
Round difficulty - Easy

Web Development, Databases

Round duration - 60 minutes
Round difficulty - Medium

This was the final round and was a telephonic interview.

Q1. 
Implementation of HashMap with Constant Time Operations
Design a data structure that effectively stores a key-value mapping and performs specific operations in constant time.
Explanation:
Your data stru...read more
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Q2. 
Isomorphic Trees Problem Statement
You are provided with two arbitrary binary trees. Determine if both trees are isomorphic.
Explanation:
Two binary trees are considered isomorphic if one tree can be tr...read more
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There were 3 questions in the online assessment.

1 - Binary Search
2 - DP
3 - Graphs

Q1. Implement a persistence stack with constant time operations
Ans. 
Implement a persistence stack with constant time operations
• Use a combination of a stack and a hashmap to achieve constant time operations for push, pop, and get operations

• Maintain a stack to store the elements and a hashmap to store the index of each element in the stack

• When pushing an element, add it to the stack and update its index in the hashmap

• When popping an element, remove it from the stack and also remove its i...read more
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Q1. Median of two sorted arrays and OOPs basics
Ans. 
Finding the median of two sorted arrays and discussing OOPs basics
• To find the median of two sorted arrays, merge the arrays and then calculate the median

• OOPs basics include concepts like encapsulation, inheritance, polymorphism, and abstraction

• Example: Median of [1, 3] and [2] is 2.0
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Round duration - 120 Minutes
Round difficulty - Medium

Q1. 
Inorder Traversal of Binary Tree
You are provided with a Binary Tree composed of 'N' nodes, each holding integer values. Your task is to compute the Inorder traversal of this binary tree.
Example:
For t...read more
Ans. 
The task is to find the in-order traversal of a given binary tree.
• Implement a recursive function to perform in-order traversal of the binary tree

• Start from the left subtree, then visit the root node, and finally visit the right subtree

• Use an array to store the values of the nodes in the in-order traversal
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Round duration - 50 minutes
Round difficulty - Medium

Interview on google meet

Q1. Given two tables, how would you return an inner join on a common column (key)?
Ans. 
The inner join operation combines rows from two tables based on a common column (key).
• Use the JOIN keyword in the SQL query to perform an inner join.

• Specify the common column (key) in the ON clause of the join.

• The result will contain only the matching rows from both tables.
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Round duration - 50 minutes
Round difficulty - Medium

Q1. 
Search in a Row-wise and Column-wise Sorted Matrix Problem Statement
You are given an N * N matrix of integers where each row and each column is sorted in increasing order. Your task is to find the positi...read more
Ans. 
Given a sorted matrix, find the position of a target integer in the matrix.
• Iterate through each row and column of the matrix

• Compare the target integer with the current element

• If the target integer is found, return the position

• If the target integer is not found, return {-1, -1}
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Round duration - 3 Hours
Round difficulty - Hard

3 Coding questions ( 1 medium graph dfs based question , 2 hard level prefix array question ans 3 was a hard question which I don't remember)

2 Database question ( It mostly includes joining 2-3 tables and then you would be able to solve it)

Q1. 
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. Flood Fill Algorithm
We can use the flood fill algorithm to check for all connected 1s.
 
• We create two arrays, dx, and dy, in which we store the unit vectors for all eight directions. Thus, when we are at a given cell, we can easily check for all its adjacent cells by simply looping over the two arrays, adding their values to the current position, and checking for this new position recursively.
• We will also create a ...read more
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Q2. 
Maximum Product Subarray Problem Statement
Given an array of integers, determine the contiguous subarray that produces the maximum product of its elements.
Explanation:
A subarray can be derived from th...read more
Ans. Brute-force
Steps:
1. Create an ans variable and initialize it to INT_MIN.
2. Run a loop i = 0 to N and do:
   • Run a loop j = i to N and do:
     • Create a variable, say currentProduct and initialize it to 1.
     • Run a loop k = i to j and do:
       • currentProduct = currentProduct * arr[k]
       • Store the maximum of ans and the currentProduct in the ans variable.
3. Finally, return the ans variable.
Space Complexity: O(1)Explanation:
O(1)
 
Constant space is u...read more
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Q3. You were given 3-4 models in a DBMS context. How did you join those models to obtain the desired result?
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Round duration - 30 minutes
Round difficulty - Medium

These rounds depends on the type of interviewer.
My friends were asked questions from DSA but from me they asked a lot of questions on Node.JS and React.

Round duration - 30 Minutes
Round difficulty - Medium

This round depends on your interviewer.
My colleagues were asked questions from DS but my interviewer focused just on javascript.

Round duration - 45 minutes
Round difficulty - Easy

It was a managerial round they will test your communication and how well do you handle situations in your life

Q1. What is one of the most challenging situations you have faced in your life, and how did you handle it?
Ans. 
Tip 1 : just be confident and communicate with them
 
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Round duration - 90 minutes
Round difficulty - Medium

3 DSA questions, 2 SQL questions
On the DoSelect platform, which was good

Q1. 
Matrix Chain Multiplication Problem
Given 'N' 2-dimensional matrices and an array ARR of length N + 1, where the first N integers denote the number of rows in each matrix and the last integer represents t...read more
Ans. 
It was a straightforward application of the matrix multiplication approach of DP
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Q2. 
Linear Probing in Hashing
Hashing is a technique to map large non-negative integers to smaller indices using a hash function. In the context of collision resolution in hash tables, 'Linear Probing' is emp...read more
Ans. Linear Probing
The approach is pretty simple. We just need to find the mapping index and if it is occupied, we need to search for the next available index.
 
The algorithm for the same is as follows:
• Create an array HASH_TABLE of size N.
• Initialise every value of HASH_TABLE as -1.
• Loop for each KEY:
  • Initialize HASH = KEY % N
  • If HASH_TABLE[ HASH ] is already occupied, we perform:
    • while(HASH_TABLE[ HASH ] != -1):
      • HASH = ( HAS...read more
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Round duration - 60 minutes
Round difficulty - Easy

Started off with introductions and projects related questions.
Basic javascript and CSS property-related questions.
An easy DSA question

Q1. 
Pair Sum Problem Statement
You are given an array of integers 'ARR' with a length 'N' and a specific integer 'Target'. Your objective is to determine and return all pairs of elements within the array whos...read more
Ans. Hashing Solution
• We can store the frequency of every element in the array in a hashmap.
• We will loop over every index i, and check the frequency of (Target - ARR[i]) is the hashmap:
  • If (Target - ARR[i]) is equal to ARR[i], we will check if frequency of ARR[i] . If it is greater than 1 then we will decrease the frequency of ARR[i] by 2 and add a pair (ARR[i] , ARR[i]) to our answer.
  • Else, if the frequency of ARR[i] and Targ...read more
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Round duration - 45 minutes
Round difficulty - Easy

Introduction and two easy to medium DSA questions

Q1. 
Implementing Queue with Two Stacks
Your task is to implement a queue using two stacks. You are provided with ‘Q’ queries and need to handle them, where each query falls under one of these two operations:
...read more
Ans. Making the Enqueue operation costly
In this approach, we make sure that the oldest element added to the queue stays at the top of the stack, the second oldest below it and so on. To achieve this, we will need two stacks. 
 
First stack('STK1') is the main stack being used to store the data, while the second stack('STK2') is to assist and store data temporarily during various operations.
 
Following steps will...read more
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Q2. 
Roman Numeral to Integer Conversion
Convert a string representing a Roman numeral into its integer equivalent and return the result.
Explanation:
Roman numerals are represented by seven different symbol...read more
Ans. Recursive Approach
The key idea is to follow the rules of roman numbers which are as follows:
 
• The roman digits I, X and C are repeated up to three times in succession to form the numbers.
• When a digit of lower value is written to the right or after a digit of higher value, the values of all the digits are added.
• When a digit of lower value is written to the left or before a digit of higher value, then the value of th...read more
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