python单源最短路径——dijkstra算法

离字典，将起始节点的距离设为0，其他节点的距离设为无穷大
distances = {node: sys.maxsize for node in graph}
distances[start] = 0

# 初始化已访问节点的集合和未访以下是使用问节点D的集ijkstra合
visited = set()
unvisited算法求解最短路径的Python = set(graph)

while unvisited:
# 代码示例：

class D选择当前ijkstra距:
    def __init__(self, graph离最小的节点
, start,        current goal):
        self.graph = graph      # 邻接表_node = min(unvisited,
 key=lambda        self node: distances[node])

        # 更新.start = start当前节点的      # 起邻居节点点
        self.goal =的距离 goal        # 终点


        for neighbor in graph        self.open[current_node]:
_list = {}            if neighbor in     # open 表
        self.closed_list unvisited:
                new_distance = distances[current_node] + = {}   graph[current_node][neighbor # closed 表

        self.open_list[start]
                if new_distance] =  < distances[neighbor]:
                   0.0     # 将 distances[neighbor] = new_distance

        # 将当前起点放入 open_list 中

        self.parent = {节点标记start:为已访 None}    问，并从未访问集合中移除
        visited.add # 存储节点的父子关系。键为(current_node)
子节点，        unvisited值为父.remove(current_node)

    return节点。方便做最 distances

def print后_path(dist路径的ances,回 start溯
        self.min, end):
_dis = None    # 根             # 最短路径的长度

    def shortest_path据距离字典和终点节点(self):

        while True:
，逆向            if self打印路径.open_list is
    path = [end None:
               ]
 print('搜索    current_node =失败 end
    while current_node !=， 结束！')
                break
            distance start:
, min_node =        for neighbor in graph min(zip[current_node]:
            if(self.open_list distances[current.values(), self_node] ==.open_list.keys distances[neighbor()))      #] + graph 取出距[neighbor][current_node]:
离最小的节点
            self                path.open_list.pop.append(min_node)(neighbor)
                                                                      current_node = neighbor
                break

    path.reverse()
 # 将其从 open_list 中去除

            self    print.closed("_list[minShortest_node] = path from", distance                  # 将节点加入 closed start, "to", end,_list ":", "->".join(path))

# 示例 中

            if min_node == self.goal:                              # 如果节点为图的邻接矩阵终点
                self.min_dis = distance
表示
graph                shortest = {
   _path = [ 'Aself.goal]': {'B':                        # 5, 'C 记录从': 终1},
   点回溯的路径 'B