Barclays PLC Full Stack Developer Interview Questions and Answers

Multi tasking, multi processing, and multi programming are different approaches to managing tasks in an operating system.

• Multi tasking allows multiple tasks to run concurrently on a single processor.

• Multi processing involves multiple processors running tasks simultaneously.

• Multi programming allows multiple programs to be loaded into memory and executed concurrently.

• Examples of multi tasking operating systems include Wi...read more

Memory allocation refers to the process of assigning memory to programs during runtime.

• Stack allocation is done automatically and is limited in size.

• Heap allocation is done manually and is larger in size.

• Stack memory is used for local variables and function calls.

• Heap memory is used for dynamic memory allocation.

• Memory leaks can occur if heap memory is not properly managed.

Use a shared variable and synchronization mechanisms to ensure natural order printing of numbers.

• Create two threads, one for printing even numbers and the other for printing odd numbers.

• Use a shared variable to keep track of the current number to be printed.

• Implement synchronization mechanisms like locks or semaphores to ensure only one thread can access the shared variable at a time.

• Each thread should check if it is i...read more

Printing a matrix in spiral order

• Start from the first element and print it

• Move in a spiral order towards the center of the matrix

• Repeat until all elements are printed

Thread class and Runnable Interface are used for multithreading in Java.

• Thread class is a predefined class in Java that provides methods to create and control threads.

• Runnable interface is used to define a task that can be executed by a thread.

• Thread class implements Runnable interface.

• Thread class provides more control over threads than Runnable interface.

• Example: Thread t = new Thread(new MyRunnable()); t.start();

• Exa...read more

Linked List is a dynamic data structure while ArrayList is a static data structure.

• Linked List is best for frequent insertion and deletion operations.

• ArrayList is best for frequent access operations.

• Linked List uses more memory than ArrayList.

• ArrayList is faster than Linked List for accessing elements.

• Use Linked List when you need to frequently add or remove elements from the list.

• Use ArrayList when you need to frequen

I am not interested in a career in investment banking.

• I am more interested in a career in software development

• I enjoy problem-solving and creating innovative solutions through coding

• Investment banking does not align with my passion and skill set

I have chosen to apply to J.P. Morgan because of their reputation, global presence, and opportunities for growth.

• J.P. Morgan has a strong reputation in the financial industry.

• They have a global presence with offices in multiple countries.

• The company offers various opportunities for career growth and development.

• J.P. Morgan is known for its innovative technology solutions in the financial sector.

• I am impressed by their ...read more

Yes, I have made a mistake in my previous project.

• I underestimated the complexity of a task and ended up missing the deadline.

• I failed to properly test a feature, resulting in a bug that affected user experience.

• I accidentally deleted an important file without having a backup.

• I misunderstood a requirement and implemented a feature incorrectly.

Efficient solution to find k closest stars to earth from a list of stars and their distances.

• Use a priority queue to store the distances of stars from earth.

• Iterate through the list of stars and add their distances to the priority queue.

• Pop k elements from the priority queue to get the k closest stars to earth.

Find Nth largest element in the BST

• Traverse the BST in reverse inorder and keep track of count

• If count equals N, return the current node's value

• If count exceeds N, stop traversing and return null

• If count is less than N, continue traversing

Find node in BST with value equal to or greater than input value.

• Start at root node

• If input value is less than current node value, move to left child

• If input value is greater than or equal to current node value, move to right child

• Repeat until node with desired value is found or null is reached

Program to check if a binary tree is balanced

• Calculate height of left and right subtrees recursively

• Check if the difference in height is not more than 1

• Repeat for all nodes in the tree

• Time complexity: O(nlogn) or O(n)

• Space complexity: O(h) where h is the height of the tree

Find max size of a sub-string with no duplicate characters in a given string.

• Use a sliding window approach with two pointers.

• Maintain a hash set to keep track of unique characters.

• Update the maximum length of the substring as you iterate through the string.

A hash table is a data structure that stores key-value pairs and uses a hash function to map keys to buckets.

• Hash function takes a key and returns an index to a bucket

• Collisions occur when multiple keys map to the same bucket

• Collision resolution techniques include chaining and open addressing

• Example: Dictionary in Python uses hash tables to store key-value pairs

WAP to find a continuous subset divisible by 7 from an array of numbers. Calculate algorithm complexity.

• Iterate through the array and calculate the prefix sum modulo 7 at each index.

• Store the prefix sum modulo 7 in a hash table with the index as the value.

• If a prefix sum modulo 7 is already in the hash table, the subarray between the two indices has a sum divisible by 7.

• Time complexity is O(n) and space complexity is O

Given a 2D array of integers, set rows and columns to 1 if they contain 1.

• Iterate through the array to find the index of 1

• Use two arrays to keep track of rows and columns with 1

• Iterate through the rows and columns arrays to set values to 1

Code to find sum of two numbers stored as linked list.

• Traverse both lists simultaneously and add corresponding nodes

• Keep track of carry and add it to next sum

• Create a new node for each sum and move to next node

Code to print elements on path from root to leaf node with max sum

• Traverse the tree and keep track of the maximum sum path

• Use recursion to traverse the tree

• Print the path when a leaf node with maximum sum is reached

Retrieving min element from a max heap has a time complexity of O(log n).

• The min element is always the leftmost leaf node in the last level of the heap.

• To retrieve it, swap it with the last element in the heap and remove it.

• Then, bubble down the new root to maintain the max heap property.

• Examples: retrieving the smallest number in a priority queue implemented as a max heap.

• Examples: retrieving the smallest element in a

The fastest method to sort an almost sorted array is shell sort.

• Shell sort has a time complexity of O(n log n) which is faster than bubble sort and insertion sort.

• Quick sort and merge sort have a time complexity of O(n log n) but they are not optimized for almost sorted arrays.

• Shell sort works by comparing elements that are far apart first and then gradually reducing the gap between them.

• Example: If the array is [1, 3,...read more

A zombie process is a process that has completed execution but still has an entry in the process table.

• Zombie processes occur when a parent process does not properly wait for its child process to terminate.

• The zombie process remains in the process table until the parent process reads its exit status.

• Zombie processes do not consume system resources but can accumulate if not properly handled.

• They can be identified using ...read more

Hash tables have complexities related to collisions, resizing, and choosing a good hash function.

• Collisions occur when two keys map to the same index, requiring a collision resolution strategy.

• Resizing can be expensive as all elements need to be rehashed and moved to new locations.

• Choosing a good hash function is important to minimize collisions and ensure even distribution of keys.

• Examples of collision resolution stra...read more

Algorithm to find any three numbers in an array that sum to zero.

• Sort the array in ascending order.

• Loop through the array and fix the first number.

• Use two pointers to find the other two numbers that sum to the negative of the fixed number.

• If found, return the three numbers.

• If not found, move to the next number and repeat the process.

• Time complexity: O(n^2)

Returning kth smallest element in a BST with time complexity logn.

• Perform in-order traversal and keep track of count until kth element is reached

• If kth element is found, return it

• If kth element is not found, continue traversal

• If traversal is complete and kth element is not found, return null

• Time complexity is logn as we only traverse the height of the tree