Microsoft Interview Questions

Ever wondered what it’s like to sit in the interviewers chair at Microsoft? I for one wouldn’t want to find myself there, but the interview questions are fun and sometimes funny and typically are broken down into a riddle, questions about algorithms, applications, and thinker type questions. Some of my favorites:


1. Imagine you are standing in front of a mirror, facing it. Raise your left hand. Raise your right hand. Look at your reflection. When you raise your left hand your reflection raises what appears to be his right hand. But when you tilt your head up, your reflection does too, and does not appear to tilt his/her head down. Why is it that the mirror appears to reverse left and right, but not up and down?

2. One train leaves Los Angeles at 15mph heading for New York. Another train leaves from New York at 20mph heading for Los Angeles on the same track. If a bird, flying at 25mph, leaves from Los Angeles at the same time as the train and flies back and forth between the two trains until they collide, how far will the bird have traveled?

3. If you have two buckets, one with red paint and the other with blue paint, and you take one cup from the blue bucket and poor it into the red bucket. Then you take one cup from the red bucket and poor it into the blue bucket. Which bucket has the highest ratio between red and blue? Prove it mathematically.

4. How many manhole covers are there in the USA?

Algorithms (If you can answer these, kudos to you, I couldn’t! :) )

1. Suppose you have an array of 1001 integers. The integers are in random order, but you know each of the integers is between 1 and 1000 (inclusive). In addition, each number appears only once in the array, except for one number, which occurs twice. Assume that you can access each element of the array only once. Describe an algorithm to find the repeated number. If you used auxiliary storage in your algorithm, can you find an algorithm that does not require it?

2. Implement an algorithm that takes two strings as input, and returns the intersection of the two, with each letter represented at most once. Now speed it up. Now test it.

3. How would you print out the data in a binary tree, level by level, starting at the top?

4. Imagine this scenario:
I/O completion ports are communication ports which take handles to files, sockets, or any other I/O. When a Read or Write is submitted to them, they cache the data (if necessary), and attempt to take the request to completion. Upon error or completion, they call a user-supplied function to let the users application know that that particular request has completed. They work asynchronously, and can process an unlimited number of simultaneous requests.
Design the implementation and thread models for I/O completion ports. Remember to take into account multi-processor machines.


1.  How can computer technology be integrated in an elevator system for a hundred story office building? How do you optimize for availability? How would variation of traffic over a typical work week or floor or time of day affect this?

2.  Define a user interface for indenting selected text in a Word document. Consider selections ranging from a single sentence up through selections of several pages. Consider selections not currently visible or only partially visible. What are the states of the new UI controls? How will the user know what the controls are for and when to use them?

3.  How would you design a coffee-machine for an automobile.

4. How would you go about building a keyboard for 1-handed users?


1.  How would you explain how to use Microsoft Excel to your grandma?

2. Suppose you go home, enter your house/apartment, hit the light switch, and nothing happens – no light floods the room. What exactly, in order, are the steps you would take in determining what the problem was?

3. How are M&Ms made?

4. You have been assigned to design Bill Gates bathroom. Naturally, cost is not a consideration. You may not speak to Bill.

News Source: Sells Brothers

There Are 16 Comments

  1. Good thing that I am not interviewing for MS. I would most likely not get hired! Then again, I am in the Maintenance field and not the technology field.

    I always hated these kingds of questions in math. However, the last few questions, I can do well with.

  2. Some of them are fun to sit and ponder how you would actually respond to them. I mean how many people really know how M&M’s are made? We don’t care we just like to eat them…but I am sure they get some creative stories.

  3. Well after reading this it tells me one thing.

    I will never work at microsoft :)

    They also ask (used to?) the question why are manhole covers round.

  4. Yeah, I wouldn’t stand a chance working at Microsoft or Google. My brain doesn’t think that way :) I also read that some people spend days “studying” for the interview. Absolutely crazy.

  5. Ryan wrote:
    Some of them are fun to sit and ponder how you would actually respond to them. I mean how many people really know how M&M’s are made? We don’t care we just like to eat them…but I am sure they get some creative stories.

    Ummm…I actually know how M&M’s are made. I also work in the food manufacturing industry.

  6. Well, it actually bugged me so I had to go look. here is what I found:


  7. Are there actually solutions to all of these?

  8. I’m sure that most of them they just want to see how creative you can be. Is there really a right answer for designing a coffee machine for a car?

  9. Of course. It shouldn’t make coffee. Awful stuff.

  10. Haha, that mirror question is an interesting one. Although some basic knowledge of optics and human anatomy reveals the answer.

    On another note: Nate the Great?? Come now, why must everyone steal my name! (Yes, I know the books are awesome, but really!)

  11. Hmmm, maybe I should change my name to Nate. I’ll be the “Greater Nater” :D

  12. Hey now! I’ve got a trademark on Nate The Great so if you wanna take me to court be my guest :)

    i need the money anyway :P

  13. Pfft, I trademarked that back when I was 5yrs old! I have a lawsuit with the book publisher to prove it!!

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