Dijkstra算法的Python代码

以下是Dijkstra算法的Python代码：

import heapq

def dijkstra(graph, start):
    # 初始化距离字典和堆
    distances = {node: float('inf') for node in graph}
    distances[start] = 0
    heap = [(0, start)]
    
    while heap:
        # 从堆中弹出距离最短的节点
        (current_distance, current_node) = heapq.heappop(heap)
        
        # 如果当前节点的距离已经大于已知的最短距离，则忽略
        if current_distance > distances[current_node]:
            continue
        
        # 对当前节点的所有邻居进行松弛操作
        for neighbor, weight in graph[current_node].items():
            distance = current_distance + weight
            if distance < distances[neighbor]:
                distances[neighbor] = distance
                heapq.heappush(heap, (distance, neighbor))
    
    return distances

其中，`graph`是一个邻接表表示法的图，`start`是起点。算法返回一个字典，其中每个节点的键值对表示该节点到起点的最短距离。