10+ Digi Sidekick Interview Questions and Answers

Reverse words in a string word by word, removing leading/trailing spaces and extra spaces between words.

• Split the input string by spaces to get individual words

• Reverse the order of the words

• Join the reversed words with a single space in between

The task is to determine the minimum number of platforms needed at a railway station based on arrival and departure times of trains.

• Sort the arrival and departure times in ascending order.

• Use two pointers to track overlapping schedules.

• Increment platform count when a new train arrives before the previous one departs.

Return the index of the vector with the longest length palindrome

• Iterate through each string in the vector

• Check if the string is a palindrome

• Track the index of the longest palindrome string

Implement stack using queue and return triplets with given target sum

• To implement stack using queue, we can use two queues and alternate between them for push and pop operations

• For returning triplets with given target sum, we can use a nested loop and a hash set to store visited elements

• We can then iterate through the array and check if the difference between target sum and current element exists in the hash set

Convert a number to its English form for reading.

• Break the number into groups of three digits

• Convert each group to English words

• Combine the words with appropriate thousand/million/billion suffixes

Abstract class can have implementation while interface cannot. Classes can implement multiple interfaces but only one abstract class.

• Abstract class can have constructors while interface cannot.

• Abstract class can have non-abstract methods while interface cannot.

• Interfaces are used for full abstraction while abstract classes are used for partial abstraction.

• Example: Abstract class - Animal with method eat() and subclass Dog with implementation. Interface - Runnable with method ...read more

Find length of longest subarray with all unique elements in an integer array.

• Use a sliding window approach to keep track of unique elements in the subarray.

• Use a set to store unique elements and update the window accordingly.

• Iterate through the array and update the window size based on unique elements.

Delete nth node from end of linked list

• Use two pointers, one to traverse the list and another to keep track of the nth node from the end

• Once the nth node is reached, move both pointers until the end of the list

• Delete the node pointed by the second pointer

Design a traffic signal system

• Identify the number of lanes and intersections

• Determine the traffic flow and peak hours

• Choose appropriate sensors and controllers

• Implement a synchronization algorithm

• Consider emergency vehicle prioritization

• Include pedestrian crossing signals

• Ensure compliance with local regulations

Use a Set data structure to eliminate duplicates in an array of strings.

• Create a Set to store unique elements from the array.

• Iterate through the array and add each element to the Set.

• Convert the Set back to an array to get the array without duplicates.

Java web development frameworks include Spring, Hibernate, Struts, and Play.

• Popular Java web development frameworks include Spring, Hibernate, Struts, and Play

• Spring is a widely used framework for building enterprise Java applications

• Hibernate is an ORM framework for mapping Java objects to database tables

• Struts is a framework for building web applications using the MVC design pattern

• Play is a lightweight web framework for building scalable web applications

System design is the process of defining the architecture, components, modules, interfaces, and data for a system to satisfy specified requirements.

• Understand the requirements and constraints of the system

• Identify the key components and their interactions

• Consider scalability, reliability, and performance

• Design for flexibility and maintainability

• Use appropriate design patterns and technologies

Hashmap is a data structure that stores key-value pairs and provides constant time complexity for insertion, deletion, and retrieval.

• Hashmap uses hashing function to map keys to indices in an array

• Collisions can occur when multiple keys map to the same index, which can be resolved using separate chaining or open addressing

• Java implementation: HashMap map = new HashMap<>();

Common point in linked list refers to the node where two or more linked lists intersect.

• The common point can be found by traversing both linked lists and comparing the nodes.

• The common point can also be found by using two pointers, one for each linked list, and moving them until they meet at the common point.

• Examples include finding the intersection point of two linked lists or finding the loop in a linked list.