10+ EPAM Systems Interview Questions and Answers

Given two linked lists representing long integers, perform addition operation.

• Traverse both linked lists simultaneously, starting from the head.

• Perform addition of corresponding digits and keep track of carry.

• Create a new linked list to store the result.

• Handle cases where one list is longer than the other.

• Handle the final carry if any.

Swap kth node with kth last node in a singly-linked, non-circular linked list.

• Traverse the linked list to find its length or use two pointers to find kth and kth last nodes.

• Swap the nodes and update the pointers accordingly.

• Handle edge cases such as k being out of bounds or kth and kth last nodes being the same.

• Consider using recursion to traverse the linked list.

Add two long numbers and store the result in a third linked list.

• Create a linked list to store the result

• Traverse both input linked lists simultaneously, adding corresponding digits

• Handle carry over from addition

• If one linked list is longer than the other, handle remaining digits

• Return the resulting linked list

To print the kth last node in inorder traversal of a Binary Search Tree, we can use a modified inorder traversal algorithm.

• Perform an inorder traversal of the BST, keeping track of the nodes visited in a stack.

• Once the traversal is complete, pop k elements from the stack to get the kth last node.

• Print the value of the kth last node.

Hamming distance is the number of differing bits between two binary strings. Hamming weight is the number of 1s in a binary string.

• Hamming distance is used in error detection and correction codes.

• Hamming weight is also known as population count or popcount.

• To calculate hamming distance, XOR two numbers and count the number of 1s in the result.

• Example: Hamming distance between 1010 and 1110 is 1.

• Example: Hamming weight of 1010 is 2.

Sorting algorithms include bubble sort, insertion sort, selection sort, quick sort, merge sort, etc. Merge sort has O(nlogn) time complexity.

• Sorting algorithms are used to arrange data in a specific order.

• Merge sort is a divide and conquer algorithm that divides the input array into two halves, sorts each half, and then merges the sorted halves.

• The time complexity of merge sort is O(nlogn) because it divides the input array into halves recursively until the base case is reach...read more

Singly and doubly linked lists are linear data structures used to store and manipulate data.

• Singly linked lists use less memory than doubly linked lists

• Doubly linked lists allow for traversal in both directions

• Singly linked lists are faster for insertion and deletion at the beginning of the list

• Doubly linked lists are faster for insertion and deletion in the middle of the list

• Both have O(n) time complexity for searching

The sum of the products of all subsequences in an array of strings.

• Calculate the product of all elements in the array

• Calculate the product of all possible subsequences

• Sum up all the products of subsequences

I have followed the modular design pattern while building modules.

• I break down the software into smaller, independent modules that can be easily managed and maintained.

• I ensure each module has a clear purpose and well-defined interfaces for communication with other modules.

• I use techniques like encapsulation, abstraction, and separation of concerns to create modular designs.

• Example: Using the MVC (Model-View-Controller) pattern to separate the presentation, business logic, an...read more

The program calculates the amount of rainwater that can be trapped between buildings given an array of heights.

• Use two pointers to iterate from left and right towards the middle

• Keep track of the maximum height on the left and right for each pointer

• Calculate the trapped water at each index based on the minimum of the maximum heights on left and right

• Sum up the trapped water at each index to get the total trapped water

Program to find diameter of a tree and its time complexity

• Use Depth First Search (DFS) to find the longest path in the tree

• Calculate the diameter by summing the heights of the left and right subtrees for each node

• Time complexity is O(n) where n is the number of nodes in the tree

Delete the nth node in a linked list.

• Traverse the linked list to find the nth node and keep track of the previous node.

• Update the previous node's next pointer to skip the nth node.

• Free the memory allocated to the nth node.

Designed a system for a project involving real-time data processing and analysis.

• Utilized microservices architecture for scalability and flexibility

• Implemented message queues for asynchronous communication between components

• Used a combination of relational and NoSQL databases for different data storage needs

Print the boundary nodes of a tree.

• Boundary nodes are the leftmost and rightmost nodes of each level of the tree and the leaf nodes that are not part of the subtree.

• Traverse the tree in a clockwise direction and print the nodes as you encounter them.

• Use recursion to traverse the tree and keep track of the level and whether the node is a left or right boundary node.

The question involves solving a medium level problem related to binary trees.

• Understand the basic concepts of binary trees such as nodes, edges, and traversal methods.

• Practice implementing common operations on binary trees like insertion, deletion, and searching.

• Consider using recursion to solve problems involving binary trees.

• An example of a medium level problem could be finding the lowest common ancestor of two nodes in a binary tree.

Boundary Traversal Of tree

• Boundary traversal of a tree involves visiting the nodes of the tree in a specific order

• The order is: left boundary, leaf nodes, and right boundary

• We can use a combination of pre-order, in-order, and post-order traversals to achieve this

• Start with the root node and recursively traverse the left subtree, printing the nodes

• Then traverse the leaf nodes using an in-order traversal

• Finally, traverse the right subtree in a post-order traversal and print the...read more

The question is asking for the possible combinations of valid parentheses.

• Use backtracking to generate all possible combinations of parentheses.

• Keep track of the number of open and close parentheses to ensure they are balanced.

• Exclude invalid combinations where close parentheses appear before open parentheses.