D. Edge Deletion
题意
the length of the shortest path from vertex 1 to vertex i as $d_i$ .
You have to erase some edges of the graph so that at most k edges remain. Let’s call a vertex i good if there still exists a path from 1 to i with length $d_i$ after erasing the edges.
Your goal is to erase the edges in such a way that the number of good vertices is maximized.