Preparing for advanced algorithms exam (CS450 at EPFL), and I just truly understood a problem. First reaction is: "TIL prefix sum is a stack. So powerful!".
You are given a cycle of n vertices with an additional set T of edges between these n vertices (in addition to the n edges that form the cycle). You are to determine whether it is possible to draw the edges of T inside the cycle in such a manner that no two edges cross. Develop a parallel algorithm that runs on O(logn) time and uses linear total work to solve this problem.