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How to check u-v can be arbitrarily negative length using Floyd Warshall algorithm?
By nvson2201, history, 4 years ago, In English

If i have q query [start, end] in the graph. How to check whether:

the length of start to end can be arbitrarily negative length?

0  floydWarshall(matrix, n) // RUN THE FLOYD WARSHALL ALGORITHM
1  FOR (start, end) in q:
2  check = false
2  while(start != end)
3     start = Next(start)
4     if (dist[start][start] < 0)
5          check = true, break
6  if check == true
7     return "Negative Loop here"

I try the code like above and get Time limit because I have a while loop inside which is to find negative loop in the path from start to end.

Can you help me find another method?

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4 years ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

not sure if I understand the problem because it seems kind of silly but all shortest-paths will be "arbitrarily negative" iff the graph contains any negative cycles at all

edit: actually, more information is necessary, I assumed that the graph was undirected and connected

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