What method do you use to find the missing number in an integer array of 1 to 100?

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.