Allocate Books

Given an array of integers A of size N and an integer B.

The College library has N books. The ith book has A[i] number of pages.

You have to allocate books to B number of students so that the maximum number of pages allocated to a student is minimum.

1. A book will be allocated to exactly one student.
2. Each student has to be allocated at least one book.
3. Allotment should be in contiguous order, for example: A student cannot be allocated book 1 and book 3, skipping book 2.

Calculate and return that minimum possible number.

NOTE: Return -1 if a valid assignment is not possible.

1 <= N <= 10⁵
1 <= A[i], B <= 10⁵

The first argument given is the integer array A. The second argument given is the integer B.

Return that minimum possible number.

A = [12, 34, 67, 90]
B = 2

A = [5, 17, 100, 11]
B = 4

113

100

There are two students. Books can be distributed in following fashion : 
1)  [12] and [34, 67, 90]
    Max number of pages is allocated to student 2 with 34 + 67 + 90 = 191 pages
2)  [12, 34] and [67, 90]
    Max number of pages is allocated to student 2 with 67 + 90 = 157 pages 
3)  [12, 34, 67] and [90]
    Max number of pages is allocated to student 1 with 12 + 34 + 67 = 113 pages
    Of the 3 cases, Option 3 has the minimum pages = 113.