dijsktra函数代码

以下是Dijkstra算法的Python实现：

import heapq

def dijkstra(graph, start):
    # 初始化距离字典，将所有节点距离设置为无穷大，起点距离为0
    dist = {node: float('inf') for node in graph}
    dist[start] = 0
    
    # 初始化堆，将起点加入堆中
    heap = [(0, start)]
    
    while heap:
        # 取出堆顶元素
        (curr_dist, curr_node) = heapq.heappop(heap)
        
        # 如果当前节点已经被处理过，忽略它
        if curr_dist > dist[curr_node]:
            continue
            
        # 遍历当前节点的邻居节点
        for neighbor, weight in graph[curr_node].items():
            # 计算从起点到邻居节点的距离
            new_dist = dist[curr_node] + weight
            
            # 如果新的距离比已有的距离更短，则更新距离字典和堆
            if new_dist < dist[neighbor]:
                dist[neighbor] = new_dist
                heapq.heappush(heap, (new_dist, neighbor))
    
    return dist

其中，`graph`是一个字典，键为节点，值为该节点的邻居节点和对应的边权重。`start`是起点节点。函数返回一个字典，键为节点，值为起点到该节点的最短距离。