Question

我目前正在玩着名的Dijkstra算法，并且有点卡住了。我试图修改伪代码以获取源和目标的输入，努力在实现的图形中找到两个顶点之间的SHORTEST路径。我希望输入SOURCE和DEST为字符串值。我也在尝试修改，所以输入只是列表SHORTEST PATH。关于如何修改算法来获取此问题的任何想法？

1:  function Dijkstra(Graph, source):
2:  for each vertex v in Graph: // Initialization
3:  dist[v] := infinity // initial distance from source to vertex v is set to infinite
4:  previous[v] := undefined    // Previous node in optimal path from source
5:  dist[source] := 0   // Distance from source to source
6:  Q := the set of all nodes in Graph  // all nodes in the graph are unoptimized - thus are in Q
7:  while Q is not empty:   // main loop
8:  u := node in Q with smallest dist[ ]
9:  remove u from Q
10: for each neighbor v of u:   // where v has not yet been removed from Q.
11: alt := dist[u] + dist_between(u, v)
12: if alt < dist[v]    // Relax (u,v)
13: dist[v] := alt
14: previous[v] := u
15: return previous[ ]

Answer 1

简单，将DESTINATION添加为您的函数接受作为输入的参数，并像往常一样继续算法。只需删除最后一行

return previous[ ]

添加以下行，仅为最短路径中的节点访问前一个[]列表。您从DEST节点开始此遍历，直到您到达SOURCE

x := DEST
shortest_path := []
while x is not equal to SOURCE:
       shortest_path.add(x)
       x := previous[x]
 shortest_path.add(x) //finally add the SOURCE outside the loop
 return shortest_path[]

要将SOURCE和DEST作为字符串值，您需要一个带有字符串的例程，并返回该Graph中的Node，其中包含输入字符串给出的值。

Algorithm getNodeFromString(Graph G, String s):
      for every node N in G:
             if N.id == s:
                   return N

当然，这是假设Graph中的每个节点都有唯一的标识符。

Dijkstra算法的修正

1 个答案: