Explain what modifications, if any, need to be made to Diisktra's shotest path and/or graph to: (a) Solve single source shortest path problem for directed weighted graphs. (b) Find shortest path to a given vertex from each of the other vertices. (c) If there are several shortest paths, find the number of shortest paths. For example in the graph below, there are 3 shortest paths between A and D. Provide pseudo-code for the solution