Python实现Dijkstra算法

# Dijkstra.狄杰斯特拉
import heapq
import math

def init_distance(graph, s):
    distance = {s: 0}
    for vertex in graph:
        if vertex != s:
            distance[vertex] = math.inf
    return distance

def dijkstra(graph, s):
    pqueue = []
    heapq.heappush(pqueue, (0, s))
    seen = set()
    parent = {s: None}
    distance = init_distance(graph, s)

    while len(pqueue) > 0:
        pair = heapq.heappop(pqueue)
        dist = pair[0]
        vertex = pair[1]
        seen.add(s)
        nodes = graph[vertex].keys()
        for w in nodes:
            if w not in seen:
                if dist + graph[vertex][w] < distance[w]:
                    heapq.heappush(pqueue, (dist + graph[vertex][w], w))
                    parent[w] = vertex
                    distance[w] = dist + graph[vertex][w]
    return parent, distance

if __name__ == '__main__':
    graph_dict = {
        "A": {"B": 5, "C": 1},
        "B": {"A": 5, "C": 2, "D": 1},
        "C": {"A": 1, "B": 2, "D": 4, "E": 8},
        "D": {"B": 1, "C": 4, "E": 3, "F": 6},
        "E": {"C": 8, "D": 3},
        "F": {"D": 6},
    }

    parent_dict, distance_dict = dijkstra(graph_dict, "A")
    print(parent_dict)
    print(distance_dict)