Microsoft Software Developer Mock Interview
Practice 30 Microsoft Software Developer interview questions covering algorithms, system design, and coding assessments.
Question 1 of 30
What method do you use to find the missing number in an integer array of 1 to 100?
How to Answer
Example Answer
Community Answers
William Swansen has worked in the employment assistance realm since 2007. He is an author, job search strategist, and career advisor who helps individuals worldwide and in various professions to find their ideal careers.
When it comes to interview questions about finding missing numbers in an integer, that tells me that the interviewer at Microsoft has a specific type of role in mind for a candidate. More than likely, they are looking for an analytical thinker who can solve problems relatively easily. Let me demonstrate. Let's say I have an array number from 1 to 100. These are just random numbers for now. In a sorted array, you can compare whether a number is equal to the expected next number or not. Alternatively, you can also use the BitSet method in Java to solve this problem as well. A BitSet solution is more general, as you can use it to find more than one missing value on an integer array. Take your time to think about how you will respond to these questions because the interviewer is testing your ability to process and come up with an answer.
William Swansen has worked in the employment assistance realm since 2007. He is an author, job search strategist, and career advisor who helps individuals worldwide and in various professions to find their ideal careers.
"Having many tools at my disposal, I find that a Java solution is the best way to solve this problem. I would typically write a program to find the missing number in an array in Java, C#, or another language. The method I use is to find missing elements in an area of 100 integers, which contains numbers between 1 and 100. Looking at this problem from a high level, this can easily be solved by calculating the sum of the series using n(n1)/2 to solve this problem. It's a quick and efficient way to do it, but keep in mind that it cannot be used if the array contains more than one number or if the array contains duplicates. These solutions might require you to calculate the sum of numbers and then subtract that from the actual sum to arrive at the correct answer. Is this similar to the methodology used here at Microsoft?"
Interview Coach
Jaymie
A real coach, not AI. I read every answer myself and write back with personalized feedback.
Typically responds within 24 hours.
0 - Character Count
Unlock All 30 Microsoft Questions
Unlock expert responses shaped by Microsoft's rigorous technical interview process.
Get StartedJump to Question