PayPal Software Developer Interview Questions, Process, and Tips

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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Round duration - 60 minutes
Round difficulty - Hard

It was on hackerearth platform and duration was 60 mins.

Q1. 
Maximum Path Sum in a Matrix
Given an N*M matrix filled with integer numbers, determine the maximum sum that can be obtained from a path starting from any cell in the first row to any cell in the last row...read more
Ans. 
We are given a matrix of N * M. To find max path sum first we have to find max value in first row of matrix. Store this value in res. Now for every element in matrix update element with max value which can be included in max path. If the value is greater then res then update res. In last return res which consists of max path sum value.
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Round duration - 60 minutes
Round difficulty - Easy

Only problem solving was asked simple DSA based questions

Q1. 
Valid Parentheses Problem Statement
Given a string 'STR' consisting solely of the characters “{”, “}”, “(”, “)”, “[” and “]”, determine if the parentheses are balanced.
Input:
The first line contains an...read more
Ans. 
Declare a character stack S.
Now traverse the expression string exp. 
If the current character is a starting bracket (‘(‘ or ‘{‘ or ‘[‘) then push it to stack.
If the current character is a closing bracket (‘)’ or ‘}’ or ‘]’) then pop from stack and if the popped character is the matching starting bracket then fine else brackets are not balanced.
After complete traversal, if there is some starting bracket left in stac
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Round duration - 60 mins
Round difficulty - Easy

Problem solving and DSA

Q1. 
Find All Pairs Adding Up to Target
Given an array of integers ARR of length N and an integer Target, your task is to return all pairs of elements such that they add up to the Target.
Input:
The first line ...read more
Ans. 
This problem can be solved efficiently by using the technique of hashing. Use a hash_map to check for the current array value x(let), if there exists a value target_sum-x which on adding to the former gives target_sum. This can be done in constant time.
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Round duration - 30 minutes
Round difficulty - Easy

This was hiring manager round and it was mostly behavioural round

Round duration - 90 minutes
Round difficulty - Medium

It was conducted in Hacker rank which consisted of 10 aptitude questions that included C, C++, Java MCQ. 2 programming questions were also given.

Q1. 
Minimum Cost Path Problem Statement
Given an N x M matrix filled with integers, determine the minimum sum obtainable from a path that starts at a specified cell (x, y) and ends at the top left corner of t...read more
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Q2. 
Balanced Parentheses Combinations
Given an integer N representing the number of pairs of parentheses, find all the possible combinations of balanced parentheses using the given number of pairs.
Explanati...read more
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Round duration - 60 minutes
Round difficulty - Medium

Technical round with questions based on data structures, oops and networking.

Q1. 
Character Counting Challenge
Create a program that counts and prints the total number of specific character types from user input. Specifically, you need to count lowercase English alphabets, numeric digi...read more
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Q2. 
K Largest Elements Problem Statement
Given an unsorted array containing 'N' integers, you are required to find 'K' largest elements from the array and return them in non-decreasing order.
Input:
The fir...read more
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Q3. How can you check whether you have an internet connection on your system?
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Q4. What happens when you type a URL in a web browser?
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Round duration - 60 minutes
Round difficulty - Medium

Technical round with questions based on data structures, oops and networking.

Q1. 
Counting Sort Problem Statement
Ninja is learning about sorting algorithms, specifically those that do not rely on comparisons. Can you help Ninja implement the counting sort algorithm?
Example:
Input:
...read more
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Q2. What are the applications of the Fibonacci series in real life?
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Round duration - 30 minutes
Round difficulty - Easy

HR round where the interviewer asked questions to know more about me.

Round duration - 60 minutes
Round difficulty - Easy

I couldn't find an optimal approach to the first question, so she skipped that question and proceeded to next questions. Remaining questions I have answered satisfactorily.

Q1. 
Subset Sum Equal To K Problem Statement
Given an array/list of positive integers and an integer K, determine if there exists a subset whose sum equals K.
Provide true if such a subset exists, otherwise r...read more
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Q2. 
BFS Traversal in a Graph
Given an undirected and disconnected graph G(V, E) where V vertices are numbered from 0 to V-1, and E represents edges, your task is to output the BFS traversal starting from the ...read more
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Round duration - 60 minutes
Round difficulty - Easy

I told that my strength is problem solving and I can always find a way when there is a bottle-neck. Gave some examples of my experiences while doing my assignments.

Q1. 
Replace Spaces in a String
Given a string STR consisting of words separated by spaces, your task is to replace all spaces between words with the characters "@40".
Input:
The first line contains an integ...read more
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