Applied through career day at university.

Interviewed in their Milan office, a 1-hour process with two interviewers. The first 15-20 minutes were spent discussing myself and explaining one project in detail. Then came technical questions.

I did not pass, but it was a very nice experience. I felt very comfortable because they made me feel that way.

1. Given an array of N-1 numbers, starting from 0, with one number missing. For example, if N=5 and the array is [0, 2, 3, 4, 5], the missing number is 1. Find the missing number.

2. You have a recursive grammar with the alphabet ∑ = {(, )}. A well-defined string is one where each closing bracket has a corresponding opening bracket. You cannot close a bracket without opening one first. Examples include ()()() or ((())) or (())()((())). Your function receives a string with this alphabet as input; determine if it is well-defined.