Problem 5. (30 points) You are given an array A[0.n]. The first n positions A[0..n1] contain all but one of the positive integers 1,.,n+1, in some arbitrary order. Find which integer is missing in A[0.n1] and return it by using an algorithm that is time and space efficient. Show the correctness of your algorithm and justify your arguments(s). (Ellicient means it cannot be improved upon.)