Algorithms | Graph Shortest Paths | Question 9

Following statement is true or false?

If we make following changes to  Dijkstra, then it can be used to find 
the longest simple path, assume that the graph is acyclic.

1) Initialize all distances as minus infinite instead of plus infinite.

2) Modify the relax condition in  Dijkstra's algorithm to update distance
  of an adjacent v of the currently considered vertex u only
  if "dist[u]+graph[u][v] > dist[v]". In shortest path algo, 
  the sign is opposite. 

(A) True
(B) False

Answer: (B)
Explanation: In shortest path algo, we pick the minimum distance vertex from the set of vertices for which distance is not finalized yet. And we finalize the distance of the minimum distance vertex.

For maximum distance problem, we cannot finalize the distance because there can be a longer path through not yet finalized vertices.
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