Question

我在Python中使用Dijkstra的算法实现了一个问题。

class Graph ():
    def __init__(self):
        self.nodes = set()
        self.edges = defaultdict(list)
        self.distances = {}

    def add_node(self, value):
        self.nodes.add(value)

    def add_edge(self, from_node, to_node, distance):
        self.edges[from_node].append(to_node)
        self.edges[to_node].append(from_node)
        self.distances[(from_node, to_node)] = distance
        self.distances[(to_node, from_node)] = distance


    def dijsktra(graph, initial):
        visited = {initial: 0}
        path = {}

        nodes = set(graph.nodes)

        while nodes: 
            min_node = None
        for node in nodes:
            if node in visited:
                if min_node is None:
                    min_node = node
                elif visited[node] < visited[min_node]:
                    min_node = node

        if min_node is None:
            break

        nodes.remove(min_node)
        current_weight = visited[min_node]

        for edge in graph.edges[min_node]:
            weight = current_weight + graph.distances[(min_node, edge)]
        if edge not in visited or weight < visited[edge]:
            visited[edge] = weight
            path[edge] = min_node
        return visited, path

问题是，我需要从一个顶点到另一个顶点的所有路径。例如，如果我使用此

g = Graph()
g.add_node('a')
g.add_node('b')
g.add_node('c')
g.add_node('d')
g.add_node('e')

g.add_edge('a', 'b', 10)
g.add_edge('b', 'c', 10)
g.add_edge('a', 'c', 15)
g.add_edge('c', 'd', 20)
g.add_edge('d','e',3)
print(dijsktra(g, 'a'))

结果是：

({'a': 0, 'b': 10, 'c': 15, 'd': 35, 'e': 38}, {'b': 'a', 'c': 'a', 'd': 'c', 'e': 'd'})

我需要它看起来像这样：

({'a': 0, 'b': 10, 'c': 15, 'd': 35, 'e': 38}, {'b': 'a', 'c': 'a', 'd': 'c','a', 'e': 'd','c','a'})

因为我需要在一个地方到另一个顶点的所有路径，而不仅仅是最后一步。

Python - Dijkstra的算法

0 个答案: