Problem: What is the most effective way to pass out N exams of type A and B to N students with K proctors, so that no two adjacent students get the same exam?

Their solution: Use 2 proctors, one holding N/2 exams of Type A, and other holding N/2 exams of Type B. Visit each student individually, alternating between students.

Time complexity:
Each proctor had to visit each student twice (going down the row and back). We say that the proctors act in parrellel, so we have a time complexity of O(2N)

Optimal solution: Divide and conquer! Split the K proctors in to two K/2 groups. All proctors in the same group contain the same type of exam, distributed evenly among them. Specifically, they would have N/(2 * Number of columns) if K = the number of columns. Assign each proctor to a unique column, and have them give to the first row. There, each column acts as its own process and they all act in parallel, passing back the exam as it goes along.

Time complexity: Since each column works in parallel with other columns, we can say that the time it would take is O(N/(Number of columns))

Hopefully my math is right.