写一个dijskra算法的python代码

以下是一个基于Python的Dijkstra算法的实现：

import heapq

def dijkstra(graph, start):
    distances = {node: float('inf') for node in graph}
    distances[start] = 0
    pq = [(0, start)]
    while pq:
        (dist, current_node) = heapq.heappop(pq)
        if dist > distances[current_node]:
            continue
        for neighbor, weight in graph[current_node].items():
            distance = dist + weight
            if distance < distances[neighbor]:
                distances[neighbor] = distance
                heapq.heappush(pq, (distance, neighbor))
    return distances

这个函数接受一个字典表示的图和一个起始节点，返回一个字典表示从起始节点到每个节点的最短距离。