Twitter Interview Question for Software Engineer / Developers

Country: United States
Interview Type: Phone Interview

Comment hidden because of low score. Click to expand.
of 2 vote

You need:
1) HashTable
2) Doubly LinkedList

Each entry will have the key mapped to a struct that includes {data, prev, next} via hashmap
You also need 2 placeholder pointers: MostRecent and LeastRecent (I call them hi and lo)

When you insert entries, link the 'hi' entry to the newest entry and vice versa. update the 'hi'
When you fill up the cache (ie the array/hashmap capacity) then:
1) if you get a new data entry request (cache-miss), put it in place of 'lo' entry, and update the next and prev pointers (using hi.prev and Update 'hi' ofcourse.
2) if you get a previously entered data request (cache hit) then goto that entry (use hashmap's O(1) access) and update the prev and next pointers for that entry (using entry.prev and, update 'hi'

Good God, this is much easier to explain on paper.

- Arjan August 16, 2013 | Flag Reply
Comment hidden because of low score. Click to expand.
of 0 vote

this is a good link for LRU

- BJ August 20, 2013 | Flag Reply

Add a Comment

Writing Code? Surround your code with {{{ and }}} to preserve whitespace.


is a comprehensive book on getting a job at a top tech company, while focuses on dev interviews and does this for PMs.

Learn More


CareerCup's interview videos give you a real-life look at technical interviews. In these unscripted videos, watch how other candidates handle tough questions and how the interviewer thinks about their performance.

Learn More

Resume Review

Most engineers make critical mistakes on their resumes -- we can fix your resume with our custom resume review service. And, we use fellow engineers as our resume reviewers, so you can be sure that we "get" what you're saying.

Learn More

Mock Interviews

Our Mock Interviews will be conducted "in character" just like a real interview, and can focus on whatever topics you want. All our interviewers have worked for Microsoft, Google or Amazon, you know you'll get a true-to-life experience.

Learn More