Freecharge Interview Questions and Answers for Freshers

Q1. How to write docker file
Ans. 
A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image.
• Start with a base image using the FROM keyword

• Use the RUN keyword to execute commands in the container

• Use the COPY keyword to add files from the host machine to the container

• Use the CMD keyword to specify the command to run when the container starts
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Q2. Explain file system in linux
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File system in Linux organizes and manages data on storage devices.
• File system controls how data is stored, accessed, and managed on storage devices.

• Linux uses a hierarchical file system structure with directories and files.

• Common file systems in Linux include ext4, XFS, and Btrfs.

• File permissions in Linux determine who can read, write, or execute files.

• Mounting and unmounting drives allows access to different file sys...read more
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Q3. Few Linux commands
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Q4. Kubernetes question
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Q1. Kubernetes case based question
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Q2. Linux scripting
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The aptitude test was medium level.

Q1. Array - Pair Sum - Return pair of the sum from arrays
Ans. 
Find pairs in array that sum up to a given target value.
• Iterate through the array and store each element in a hash set.

• For each element, check if the target value minus the current element exists in the hash set.

• Return the pair of elements that sum up to the target value.
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Q2. Check if two strings are anagram of each other
Ans. 
Check if two strings are anagram of each other
• Create character count arrays for both strings

• Compare the character count arrays to check if they are equal

• Example: 'listen' and 'silent' are anagrams
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Q1. Number of subset
Ans. 
Calculate the number of subsets of a given set
• The number of subsets of a set with n elements is 2^n

• Include the empty set and the set itself in the count

• For example, a set with 3 elements will have 2^3 = 8 subsets
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Q2. Remove kth node from end
Ans. 
Remove the kth node from the end of a linked list.
• Use two pointers, one to traverse the list and another to keep track of the kth node from the end.

• Once the first pointer reaches the end, the second pointer will be at the kth node from the end.

• Adjust the pointers to remove the kth node.
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Q1. Whatsapp low level design
Ans. 
Whatsapp low level design involves messaging, encryption, media sharing, and user authentication.
• Use end-to-end encryption to secure messages

• Implement message queues for real-time message delivery

• Allow media sharing through file transfer protocols

• Use OAuth for user authentication and authorization
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Q2. Lru implemention
Ans. 
Implementing an LRU (Least Recently Used) cache to efficiently manage memory and optimize data retrieval.
• Use a hash map for O(1) access to cache items.

• Utilize a doubly linked list to maintain the order of usage.

• On cache hit, move the accessed item to the front of the list.

• On cache miss, add the new item to the front and evict the least recently used item from the back.

• Example: If cache size is 2, accessing keys 1, 2, a...read more
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Q1. 1. Merge Two Sorted Linked List. 2. String Pool, String Builder, String Buffer 3. Shallow Copy, Deep Copy. 4. Fail-Fast, Fail safe Iterator 5. Java 8 features you know 6. Stream related question 7. Basic J...read more
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Q1. 1. Multithreading Concepts (Threads, Process, Thread Pool, etc) 2. coding questions -> T1 = Free and T2 = Charge: Print Free Charge using multithreading concept. 3. Basic Questions of Spring Boot(@RestCont...read more
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