7 Classes Interview Questions and Answers

Regex for email validation

• Start with a string of characters followed by @ symbol

• Followed by a string of characters and a period

• End with a string of characters with a length of 2-6 characters

• Allow for optional subdomains separated by periods

• Disallow special characters except for . and _ in username

Print prime numbers in a given range and optimize the solution.

• Use Sieve of Eratosthenes algorithm to generate prime numbers efficiently

• Start with a boolean array of size n+1, mark all as true

• Loop through the array and mark all multiples of each prime as false

• Print all the indexes that are still marked as true

Find angle between hour and minute hand in a clock given the time.

• Calculate the angle made by the hour hand with respect to 12 o'clock position

• Calculate the angle made by the minute hand with respect to 12 o'clock position

• Find the difference between the two angles and take the absolute value

• If the angle is greater than 180 degrees, subtract it from 360 degrees to get the smaller angle

To un-hash a string, use a reverse algorithm to convert the hash back to the original string.

• Create a reverse algorithm that takes the hash as input and outputs the original string

• Use the same logic as the hash function but in reverse order

• If the hash function used a specific algorithm, use the inverse of that algorithm to un-hash the string

Bubble sort is a simple sorting algorithm that repeatedly steps through the list, compares adjacent elements and swaps them if they are in the wrong order.

• Start from the first element and compare it with the next element

• If the first element is greater than the next element, swap them

• Repeat this process for all elements in the list

• Continue this process until no more swaps are needed

A Turing Machine is a theoretical device that can simulate any algorithmic computation.

• It was proposed by Alan Turing in 1936 as a model for computation.

• It consists of a tape, a head that can read and write symbols on the tape, and a set of rules for transitioning between states.

• It can simulate any algorithmic computation, making it a powerful tool for theoretical computer science.

• It is often used as a theoretical basi...read more

A hash function is a mathematical function that converts input data of arbitrary size into a fixed-size output.

• Hash functions are used to index data in hash tables.

• They are also used in cryptography to securely store passwords.

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