Crest Infosystems Interview Questions and Answers

2 papers- Online tricky questions-medium to high-level difficulty. Computer based

Q1. Basic Biology conceptual questions- What is DNA?
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Q2. How does pasteurization work?
Ans. 
Pasteurization is a process of heating food or liquid to a specific temperature to kill harmful bacteria and increase shelf life.
• The process involves heating the substance to a temperature between 60-100°C for a specific time period.

• This kills most of the harmful bacteria and pathogens present in the substance.

• The process was developed by Louis Pasteur in the 19th century to prevent spoilage of wine and beer.

• Pasteuriza...read more
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Q3. Difference between mean, median, and mode?
Ans. 
Mean is the average of a set of numbers, median is the middle value, and mode is the most frequently occurring value.
• Mean is calculated by adding up all the numbers in a set and dividing by the total number of values.

• Median is the middle value in a set of numbers when they are arranged in order.

• Mode is the value that appears most frequently in a set of numbers.

• In a symmetrical distribution, the mean, median, and mode a...read more
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Round duration - 150 Minutes
Round difficulty - Medium

3 coding question + 50 dsa

Q1. 
Majority Element Problem Statement
Given an array/list 'ARR' consisting of 'N' integers, your task is to find the majority element in the array. If there is no majority element present, return -1.
Exampl...read more
Ans. 
Find the majority element in an array, return -1 if no majority element exists.
• Iterate through the array and keep track of the count of each element using a hashmap.

• Check if any element's count is greater than floor(N/2) to determine the majority element.

• Return the majority element or -1 if no majority element exists.
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Q2. 
Height of a Binary Tree
You are provided with an arbitrary binary tree consisting of 'N' nodes where each node is associated with a certain value. The task is to determine the height of the tree.
Explana...read more
Ans. 
Calculate the height of a binary tree given its level order traversal.
• Traverse the binary tree level by level and keep track of the height as you go down the tree.

• Use a queue data structure to perform level order traversal efficiently.

• The height of a binary tree is the maximum number of edges from the root to any leaf node.

• Handle NULL nodes represented by -1 in the input.

• Return the height of the binary tree as a single...read more
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Q3. 
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 count the number of connected components.

• Maintain a visited array to keep track of visited cells to avoid counting the same island multiple times.

• Iterate through each cell in the matrix and if it is a land (1) and not visited, perform DFS/BFS to explore the connected land cells.

• I...read more
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Round duration - 60 Minutes
Round difficulty - Hard

2 coding questions

Q1. 
Maximum Length Pair Chain Problem Statement
You are given 'N' pairs of integers where the first number is always smaller than the second number, i.e., in pair (a, b) -> a < b always. A pair chain is...read more
Ans. 
Find the length of the longest pair chain that can be formed using the given pairs.
• Sort the pairs based on the second element in ascending order.

• Iterate through the sorted pairs and keep track of the maximum chain length.

• Update the chain length if the current pair can be added to the chain.

• Return the maximum chain length at the end.
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Q2. 
Maximize Stock Trading Profit
You are given an array prices, representing stock prices over N consecutive days. Your goal is to compute the maximum profit achievable by performing multiple transactions (i...read more
Ans. 
Find maximum profit by buying and selling stocks multiple times.
• Iterate through the array and find all increasing sequences of stock prices.

• Calculate profit by buying at the start and selling at the end of each increasing sequence.

• Sum up all profits to get the maximum profit achievable.
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Round duration - 45 minutes
Round difficulty - Medium

Data structures,java script,web dev related questions,dbms questions

Q1. Can you describe how to design a web crawler?
Ans. 
Designing a web crawler involves defining the scope, selecting a crawling strategy, implementing the crawler, handling data storage, and ensuring politeness.
• Define the scope of the web crawler by determining the websites to crawl and the depth of the crawl.

• Select a crawling strategy such as breadth-first or depth-first search based on the requirements.

• Implement the web crawler using a programming language like Python o...read more
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Basic aptitude questions. Just keep a track of time

2nd round is coding round. You can expect Leetcode medium questions. The topics asked are Linked list, Trees and arrays.

3rd round is again the Coding Test. Level of questions is Leetcode Medium to Leetcode Hard. Topics covered are Trees, Doubly Linked List, Dp etc.

Q1. 4th round is an hour-long technical interview. The interviewer will start by asking about your introduction and you can expect some questions about your introduction or projects. The rest of the time is gi...read more
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Q2. The questions were House Robber 3 from leetcode and some questions based on the binary array.
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