Paytm Money Backend Developer Interview Questions, Process, and Tips

Round duration - 90 Minutes
Round difficulty - Medium

Q1. 
Cycle Detection in a Singly Linked List
Determine if a given singly linked list of integers forms a cycle or not.
A cycle in a linked list occurs when a node's next points back to a previous node in the ...read more
Ans. 
Detect if a singly linked list forms a cycle by checking if a node's next points back to a previous node.
• Use Floyd's Cycle Detection Algorithm to determine if there is a cycle in the linked list.

• Maintain two pointers, one moving at double the speed of the other, if they meet at any point, there is a cycle.

• If one of the pointers reaches the end of the list (null), there is no cycle.
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Q2. 
Next Greater Element Problem Statement
Given a list of integers of size N, your task is to determine the Next Greater Element (NGE) for every element. The Next Greater Element for an element X is the firs...read more
Ans. 
Find the Next Greater Element for each element in a list of integers.
• Iterate through the list of integers from right to left.

• Use a stack to keep track of elements for which the Next Greater Element is not yet found.

• Pop elements from the stack until a greater element is found or the stack is empty.

• Assign the Next Greater Element as the top element of the stack or -1 if the stack is empty.
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. How would you design an ATM machine?
Ans. 
Designing an ATM machine involves considering user interface, security measures, transaction processing, and hardware components.
• User interface should be intuitive and easy to navigate for users of all ages.

• Implement security measures such as PIN entry, card authentication, and encryption to protect user data.

• Transaction processing should be fast and reliable, with options for cash withdrawals, deposits, transfers, and...read more
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Round duration - 45 Minutes
Round difficulty - Easy

Q1. Why you want to switch
Ans. 
Seeking new challenges and growth opportunities in a different environment.
• Desire to work on new technologies and projects

• Opportunity for career advancement

• Seeking a better work-life balance

• Interested in a different company culture or team dynamic
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DS/ALGO and problem-solving was asked in round one

1 hour 10 mins, MERN Stack, Face to Face. Mongodb, medium DSA Question, callback, eventloop, NodeJS asynchronous working

Q1. What is the difference between a static function and a static variable?
Ans. 
Static function is a function that can only be accessed within the same file, while a static variable is a variable that retains its value between function calls.
• Static function is declared using the 'static' keyword before the return type, limiting its scope to the file it is defined in.

• Static variable is declared using the 'static' keyword before the variable type, retaining its value between function calls.

• Example o...read more
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Q2. What is the synchronization technique?
Ans. 
Synchronization technique is a method used to control access to shared resources in a multi-threaded environment.
• Synchronization techniques prevent race conditions and ensure data consistency

• Common synchronization techniques include locks, semaphores, and monitors

• Examples include using synchronized keyword in Java or mutex in C++
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Add an element to a linked list.