1. Suppose that you want to get from vertex s to vertex t in an unweighted graph G = (V, E), but you would like to stop by vertex u to eat ice-cream. Describe an efficient algorithm that would determine an optimal s-t path given your preference for stopping at u along the way. u S t 2. Compute the shortest path from u to v for ALL pairs u,v of vertices in the following graph using Floyd-Warshall algorithm. Show each step and compute D(k) matrices like we did in class. 8 2 2 5 3 1