Dijkstra 算法 python

def Dijkstra_is_algorithm(node):
    node = find_lowest_cost_node(costs)  # 在未处理的节点中找出开销最小的节点 
    while node is not None:  # 这个while循环在所有节点都被处理过后结束 
        cost = costs[node]
        neighbors = graph[node]
        for n in neighbors.key():  # 遍历当前节点的所有邻居
            new_cost = cost + neighbors[n]
            if costs[n] > new_cost:  # 如果经当前节点前往该邻居更近
                costs[n] = new_cost  # 就更新该邻居的开销
                parents[n] = node  # 同时将该邻居的父节点设置为当前节点 
        processed.append(node)  # 将当前节点标记为处理过
        node = find_lowest_cost_node(costs)  # 找出接下来要处理的节点，并循环


    def find_lowest_cost_node(costs):
        lowest_cost = float("inf")
        lowest_cost_node = None
        for node in costs:  # 遍历左右的节点
            cost = costs[node]
            if cost < lowest_cost and node not in processed:  # 如果当前节点的开销更低且未处理过
                lowest_cost = cost  # 就将其视为开销最低的节点
                lowest_cost_node = node
        return lowest_cost_node