Q1. What is a cohort retention analysis?
Cohort analysis groups users by a shared start event, usually their first activity period, and tracks behaviour over subsequent periods. Retention is the share of a cohor...
Technical Question Bank · Peer-Reviewed
Job Interview Questions and Answers Directory
Search and filter frequently asked interview questions across technical, programming, and behavioral domains. Tailor your interview preparation by difficulty for freshers or experienced developers (72 available).
Active:
Tag: bi ×
Q2. What are the four WCAG principles and the conformance levels?
WCAG is organised around four principles known as POUR. Perceivable means information must be available to the senses, for example text alternatives for images, captions ...
Q3. What is the difference between a symbol and a string?
A `Symbol` is an immutable, interned identifier such as `:name`. A `String` is a mutable sequence of characters such as `"name"`. Symbols are stored once, so repeated use...
Q4. How would you design a URL shortener like bit.ly?
Requirements: shorten a long URL, redirect quickly, handle ~100M new links per day with a 100:1 read-to-write ratio. API: POST /api/links {longUrl} -> {shortUrl}; GET /{c...
Q5. Explain Big O notation with common complexities.
Big O describes how runtime or memory grows with input size, ignoring constants and lower-order terms. From fastest to slowest: - O(1) constant: hash lookup, array index....
Q6. How do window functions work and when do you use them?
Window functions compute a value across a set of rows related to the current row without collapsing them, unlike GROUP BY. They preserve row granularity. ```sql SELECT us...
Q7. How does Redis persistence work with RDB and AOF?
Redis offers two persistence mechanisms. RDB takes point-in-time snapshots at configured intervals, for example save 900 1 snapshots after 900 seconds if at least one key...
Q8. What is the difference between aria-label and aria-labelledby?
Both give an element an accessible name, but they work differently. aria-label sets the name directly to a string, for example a button with aria-label="Close dialog". ar...
Q9. What is the difference between val and var?
`val` declares a read-only reference that cannot be reassigned after initialisation. `var` declares a mutable reference that can be reassigned. ```kotlin val name = "Ada"...
Q10. In how many ways can the letters of the word "LEVEL" be arranged?
The word LEVEL has 5 letters with repeats: L appears 2 times, E appears 2 times, V appears once. Total arrangements = 5! / (2! x 2!) = 120 / 4 = 30. Approach: start with ...