Thread: graph (depth-search) question

  1. #1
    Registered User
    Join Date
    May 2006

    graph (depth-search) question


    I got stuck at solving some problem.

    We have two cities that are connected with two roads and betwen those two paths/roads we have regional roads. We know the time that is needed to pass certain part of the road. Now I have variable x which means number of road sections.

    The diagram for x = 3 would look like:

    |        |
    |________|       first section
    |        |
    |        |
    |________|       second section
    |        |
    |        |       third section
    |        |
    One section is made of 3 roads: left, right and regional where we know the time that is needed to pass each of them.

    Now the problem I have to solve is to find the shortest path from City one to City two.
    I tried solving the problem using bruteforce (calculating all the possiblities) but in practice this is obviously a very bad solution (it takes a lot of time to calculate the shortest path if we have 1000 sections - there are 2^1000 combinations).

    Now I have came across some algorithms for solving that kind of problems (in depth-search).

    I managed to write the code that will put all the nodes in an array where each node has two pointers to other nodes (left and right) - for each crossing of the roads.

    I have no idea how should I now determine to find the shortest path (and print it).
    I know I should keep track of visited nodes, but I have no idea how to implement this?

    Any help is highly appreciated!

  2. #2
    Kernel hacker
    Join Date
    Jul 2007
    Farncombe, Surrey, England
    Have you tried searching for "shortest path search"?

    I suggest you try that first, then ask more specific problems (that would have been MUCH more efficient than your long post that you've just posted).

    [Yes, there are about 1M pages that match this, but the Wikipedia one that comes up first is probably a good starting point].

    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

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