Celebal Technologies Node JS Developer Interview Questions, Process, and Tips

Q1. String based questions in java
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Q2. What are the fundamental concepts of Java?
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Fundamental concepts of Java include OOP, platform independence, memory management, and exception handling.
• Object-oriented programming (OOP) - Java is based on classes and objects, allowing for encapsulation, inheritance, and polymorphism.

• Platform independence - Java code can run on any platform with the help of JVM (Java Virtual Machine).

• Memory management - Java has automatic garbage collection to manage memory effici...read more
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Java based questions and few DSA questions

Q1. Difference between hashset and hashtable
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HashSet is an unordered collection of unique elements, while Hashtable is a synchronized collection of key/value pairs.
• HashSet does not allow duplicate elements, while Hashtable does not allow duplicate keys.

• HashSet does not maintain insertion order, while Hashtable does not guarantee any order.

• HashSet allows null values, while Hashtable does not allow null keys or values.
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Q2. Collection vs Collections
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Collection is an interface in Java that represents a group of objects, while Collections is a utility class that contains static methods for operating on collections.
• Collection is an interface in Java that represents a group of objects.

• Collections is a utility class in Java that contains static methods for operating on collections.

• Example: List list = new ArrayList<>(); Collection collection = list;

• Example: Collections
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Q1. SQL query related questions
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Q2. Write a Java program to find the duplicate in Array
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Java program to find duplicates in an array of strings
• Create a HashSet to store unique elements

• Iterate through the array and check if element is already in the HashSet

• If element is already in the HashSet, it is a duplicate
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Basic DSA questions, best time to buy and sell stock and its variation

Q1. Basic nosql vs sql questions
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Q2. Designing system for google playstore
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1) Finding and removing loop in linked list. 2)find pair of given sum in binary tree

Q1. Print bottom view of binary tree
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Print the bottom view of a binary tree
• Use a map to store the horizontal distance and node value at each level

• Perform a level order traversal of the binary tree

• Update the map with the node value at each horizontal distance

• Print the node values in the map for the bottom view
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Q2. Oops related output based questions
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1st round is aptitude and pesudocode

Q1. Mostly python questions
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Q2. List questions and basic to mediumprogram
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In first round 4 coding question like 1 dsa 2 database and one is api and question is very simple . coding round was conducted in hackerrank

Q1. DSA QUESTION LIKE TREE AND GRAPH
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Q2. DP AND SORTING APPROACH
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Again same but dsa question and oops concept in deep level

Q1. Questions were completely based on data structures and algorithm
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Q2. SQL based questions were also asked
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