PayPal Interview Questions, Process, and Tips for Freshers

Round duration - 75 minutes
Round difficulty - Easy

Simple question based on strings was given. MCQs based on basic aptitude and programming questions were asked. 
Tips: Time management is important. Remember all the syntaxes

Q1. 
Reverse the String Problem Statement
You are given a string STR which contains alphabets, numbers, and special characters. Your task is to reverse the string.
Example:
Input:
STR = "abcde"
Output:
"e...read more
Ans. 
Reverse a given string containing alphabets, numbers, and special characters.
• Iterate through the string from the end to the beginning and append each character to a new string.

• Use built-in functions like reverse() or slicing to reverse the string.

• Handle special characters and numbers while reversing the string.

• Ensure to consider the constraints on the input string length and number of test cases.
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Round duration - 60 minutes
Round difficulty - Easy

It was a good experience.
Tips: If you don't know something just tell them. Don't try to answer something if you don't know anything about it

Q1. 
One Away Transformation Problem
Given two strings, A and B, determine whether A can be transformed into B by performing at most one of the following operations (including zero operations):
1. Delete a ch...read more
Ans. 
Determine if one string can be transformed into another by performing at most one operation (insert, delete, replace).
• Iterate through both strings simultaneously and check for differences.

• Handle cases where a character needs to be inserted, deleted, or replaced.

• Keep track of the number of operations performed and ensure it does not exceed one.
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Q2. 
Remove Duplicates from String Problem Statement
You are provided a string STR of length N, consisting solely of lowercase English letters.
Your task is to remove all duplicate occurrences of characters i...read more
Ans. 
Remove duplicate occurrences of characters in a given string.
• Use a hash set to keep track of characters seen so far.

• Iterate through the string and add non-duplicate characters to a new string.

• Return the new string without duplicate characters.
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Round duration - 30 minutes
Round difficulty - Easy

It was easy. I could answer the first question. Second one I answered really badly

Round duration - 60 minutes
Round difficulty - Easy

Technical round that lasted for around 60 minutes. The interviewer asked me questions based on DSA and OOPS concepts.

Q1. 
Dijkstra's Shortest Path Problem
Given an undirected graph with ‘V’ vertices (labeled 0, 1, ... , V-1) and ‘E’ edges, where each edge has a weight representing the distance between two connected nodes (X,...read more
Ans. 
Dijkstra's algorithm is used to find the shortest path from a source node to all other nodes in a graph with weighted edges.
• Implement Dijkstra's algorithm to find the shortest path distances from the source node to all other nodes.

• Use a priority queue to efficiently select the next node with the shortest distance.

• Update the distances of neighboring nodes based on the current node's distance and edge weights.

• Handle disc...read more
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Q2. What is the difference between C and C++?
Ans. 
C is a procedural programming language while C++ is an object-oriented programming language with features like classes and inheritance.
• C is a procedural programming language, while C++ is a multi-paradigm language with support for object-oriented programming.

• C does not support classes and objects, while C++ does.

• C does not have features like inheritance and polymorphism, which are present in C++.

• C is a subset of C++, m...read more
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Q3. What is the difference between malloc and new?
Ans. 
malloc is a function in C for dynamic memory allocation, while new is an operator in C++ for dynamic memory allocation and object creation.
• malloc is a function in C, while new is an operator in C++.

• malloc returns a void pointer, while new returns a pointer to the type being allocated.

• malloc does not call constructors, while new calls constructors for object initialization.

• malloc requires manual memory deallocation with...read more
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Q4. What is a virtual function?
Ans. 
A virtual function is a function in a base class that is declared using the keyword 'virtual' and can be overridden by a function with the same signature in a derived class.
• Virtual functions allow for dynamic polymorphism in C++

• They are used in inheritance to achieve runtime polymorphism

• Example: virtual void display() = 0; in a base class and void display() override in a derived class
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Round duration - 60 minutes
Round difficulty - Easy

Technical round that lasted for around 60 minutes. The interviewer asked me questions based on SQL and OOPS concepts.

Q1. Write a query to find the nth highest salary from a database.
Ans. 
Query to find the nth highest salary from a database
• Use the ORDER BY clause to sort salaries in descending order

• Use the LIMIT clause to select the nth highest salary

• Consider handling cases where there may be ties for the nth highest salary
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Q2. What is the difference between Stack and Heap in the context of Object-Oriented Programming (OOPS)?
Ans. 
Stack is used for static memory allocation and stores local variables, while Heap is used for dynamic memory allocation and stores objects.
• Stack is faster than Heap as it has a fixed size and memory allocation is done at compile time.

• Heap is slower than Stack as memory allocation is done at runtime and requires more complex management.

• Stack memory is limited and typically smaller in size, while Heap memory is larger an...read more
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Round duration - 30 minutes
Round difficulty - Easy

HR round that lasted for around 30 minutes. The interviewer asked questions to know more about me. We also discussed a puzzle.

Q1. You have two hourglasses, one measuring 7 minutes and the other measuring 11 minutes. How can you measure exactly 15 minutes using only these hourglasses?
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Round duration - 90 minutes
Round difficulty - Medium

This was an online test for 90 minutes. 2 programming questions and MCQs related to CS fundamentals were asked.

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.
• Traverse the linked list using two pointers, one moving one step at a time and the other moving two steps at a time.

• If the two pointers meet at any point, it indicates the presence of a cycle in the linked list.

• If one of the pointers reaches the end of the list (null), it means there is no cycle.
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Q2. 
Palindrome Partitioning II Problem Statement
Given a string ‘str’, find the minimum number of partitions needed such that every segment of the string is a palindrome.
The task is to make cuts in the stri...read more
Ans. 
Find the minimum number of partitions needed in a string such that every segment is a palindrome.
• Iterate through the string and check for palindromes at each possible partition point.

• Use dynamic programming to keep track of the minimum cuts needed.

• Consider edge cases where the string is already a palindrome or consists of different characters only.
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Round duration - 60 minutes
Round difficulty - Medium

Technical round that lasted for around 60 minutes. The interviewer asked questions related to data structures and algorithms.

Q1. 
DFS Traversal Problem Statement
Given an undirected and disconnected graph G(V, E), where V is the number of vertices and E is the number of edges, the connections between vertices are provided in the 'GR...read more
Ans. 
DFS traversal problem on an undirected and disconnected graph to find connected components.
• Perform Depth First Search (DFS) on each vertex to find connected components

• Use a visited array to keep track of visited vertices

• Print the number of connected components and list vertices in ascending order for each component
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Q2. 
Cycle Detection in Undirected Graph Problem Statement
You are provided with an undirected graph containing 'N' vertices and 'M' edges. The vertices are numbered from 1 to 'N'. Your objective is to determi...read more
Ans. 
Detect cycles in an undirected graph with given vertices and edges.
• Use Depth First Search (DFS) to traverse the graph and detect cycles.

• Maintain a visited array to keep track of visited vertices and a parent array to keep track of the parent of each vertex.

• If while traversing, you encounter a visited vertex that is not the parent of the current vertex, then a cycle exists.

• Consider edge cases like disconnected graphs an
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Round duration - 60 minutes
Round difficulty - Medium

Technical round that lasted for around 60 minutes. The interviewer asked questions related to data structures and algorithms.

Q1. 
Merge Sort Problem Statement
You are given a sequence of numbers, ARR. Your task is to return a sorted sequence of ARR in non-descending order using the Merge Sort algorithm.
Explanation:
The Merge Sort...read more
Ans. 
Implement Merge Sort algorithm to sort a sequence of numbers in non-descending order.
• Implement the Merge Sort algorithm using a Divide and Conquer approach

• Recursively divide the input array into two halves until the size of each array is 1

• Merge the sorted halves to produce a completely sorted array

• Ensure the output is in non-descending order
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Q2. 
Maximum Difference Problem Statement
Given an array ARR of N elements, your task is to find the maximum difference between any two elements in ARR.
If the maximum difference is even, print EVEN; if it is...read more
Ans. 
Find the maximum difference between any two elements in an array and determine if it is even or odd.
• Iterate through the array to find the maximum and minimum elements

• Calculate the difference between the maximum and minimum elements

• Check if the difference is even or odd and return the result
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Q3. What is hashing and how can it be implemented?
Ans. 
Hashing is a process of converting input data into a fixed-size string of bytes using a hash function.
• Hashing is used to securely store passwords by converting them into a hash value before storing in a database.

• Hashing is used in data structures like hash tables to quickly retrieve data based on a key.

• Common hash functions include MD5, SHA-1, and SHA-256.

• Hashing can be implemented in programming languages like Python
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