用pathon写出dijikstra

好的，这是一个基于Python的Dijkstra算法示例代码：

import heapq

def dijkstra(graph, start):
    # 初始化距离字典和堆
    distances = {vertex: float('infinity') for vertex in graph}
    distances[start] = 0
    heap = [(0, start)]
    
    while heap:
        # 弹出堆中最小距离的节点
        current_distance, current_vertex = heapq.heappop(heap)
        
        # 如果当前距离已经大于已知最短距离，跳过
        if current_distance > distances[current_vertex]:
            continue
        
        # 遍历当前节点的邻居节点，更新距离
        for neighbor, weight in graph[current_vertex].items():
            distance = current_distance + weight
            if distance < distances[neighbor]:
                distances[neighbor] = distance
                heapq.heappush(heap, (distance, neighbor))
    
    return distances

其中，`graph`是一个字典类型，表示图的邻接表，`start`是起点节点。示例代码中使用了堆（heap）来优化算法时间复杂度。