Given a sorted array of integers from 0 to n, write a function to find the number that introduces a problem. Your solution should have a time complexity of O(log n).

Interview question asked to Machine Learning Engineers interviewing at Pinterest, Groupon, Grammarly and others: Given a sorted array of integers from 0 to n, write a function to find the number that introduces a problem. Your solution should have a time complexity of O(log n)..