给定无向加权连通图，s，t。 找到从s到t的路径，其最大加权边缘尽可能低

Question

Given: undirected weighted connected graph. s,t are vertices.

Question: Find an algorithm as efficient as possible that returns a path from s to t. In that path, the edge that has the highest weight, will has the least weight as possible. So if we have 5 paths from s,t and for every path we have the heaviest edge, so the minimum edge of these 5.

What I've tried:

1. Use some algorithm to find the shortest path between s and t.
2. Delete all the edges that are not part of the shortest paths we've found
3. Use BFS with some modification, We run BFS depending on the number of paths from s to t. Every time we find a maximum edge and store it in an array, then we find the minimum of the array.

I'm struggling to find an algorithm that can be ran in (1), Bellman ford won't work - because it has to be directed graph. Dijkstra won't work because we don't know if it has negative circles or negative edges. And Prim is for finding MST which I'm not aware of how it can help us in finding the shortest path. Any ideas?

And other from that, If you have an algorithm in mind that can solve this question, would be much appreciated.

Answer 1

You can solve this with Kruskal's algorithm . Add edges as usual and stop as soon as s and t are in the same cluster.

The idea is that at each stage of the algorithm we have effectively added all edges below a certain weight threshold. Therefore, if s and t are in the same cluster then there is a route between them consisting entirely of edges with weight less than the threshold.

Answer 2

您可以通过转换为MST问题来解决它，基本上MST中从s到t的路径将是具有最小可能最大权重的路径

Answer 3

1. find the most negative edge in the graph
2. add that (weight+1) to every edge.
3. Now all edge are positive so you can apply Dijkstra's algorithm
4. you can get the shortest_path between source and destination
5. Now count the number of edges between source and destination (say x)
6. Real shortest path will be: shortest_path - x * (weight+1)