PhonePe Product Solution Engineer Interview Questions and Answers

The topic was -> "One nation one election"

Q1. What is a String pool in Java?
Ans. 
String pool in Java is a pool of unique strings stored in memory to optimize memory usage.
• String pool is a part of Java's memory where unique string literals are stored.

• When a new string is created, Java checks if it already exists in the pool to save memory.

• Strings created using double quotes are added to the pool, while those created using 'new' keyword are not.

• Example: String str1 = "hello"; String str2 = "hello"; /...read more
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Q2. Explain different types of exception in Java.
Ans. 
Java has checked and unchecked exceptions. Checked exceptions must be handled at compile time, while unchecked exceptions do not need to be handled explicitly.
• Checked exceptions: Must be caught or declared in the method signature. Example: IOException, SQLException

• Unchecked exceptions: Do not need to be caught or declared. Example: NullPointerException, ArrayIndexOutOfBoundsException
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Q1. Sort the list, after many queries
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Q2. LRU cache with multi level caching
Ans. 
LRU cache with multi level caching involves implementing a cache with multiple levels of storage, where the least recently used items are evicted first.
• Implement a two-level cache system with a primary cache (e.g. in-memory) and a secondary cache (e.g. disk-based).

• Use a data structure like a doubly linked list and a hash map to efficiently manage the cache and track the least recently used items.

• When an item is accesse...read more
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Q1. Basic oops, .net, c# coding, sql questions
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Q1. More coding and details on project
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Q1. More on projects and system design and troubleshooting approach
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Q1. Salary discussion
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Q1. More technical + managerial round even after HR round
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Q1. LLD HLD HM rounds
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Mcqs based on cs fundamentals and 2_3 coding questions

Q1. 2-3 DSA questions to be written on paper in the interview itself
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Q2. Merge 2 sorted Linked list into 1
Ans. 
Merge two sorted linked lists into one.
• Create a new linked list to store the merged list.

• Compare the values of the nodes from both lists and add the smaller value to the new list.

• Move the pointer of the list with the smaller value to the next node.

• Repeat the comparison and addition until one of the lists is empty.

• Add the remaining nodes from the non-empty list to the new list.

• Return the new merged list.
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Q1. A full cv analysis interview round discussion on all the projects and team work experience
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Q1. Array basics, java basics oops and all
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Medium Leetcode, Array, String, Tree, DP

Q1. System Design, Design Payment Platform
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