An array A contains all the integers from 0 to n, except for one number which is missing.
In this problem, we cannot access an entire integer in A with a single operation.
The elements of A are represented in binary, and the only operation we can use to access them is
"fetch the jth bit of A[i]," which takes constant time.
Write code to find the missing integer. Can you do it in O(n) time?