python最短路径算法dijkstra

以下是Python实现Dijkstra算法求最短路径的示例代码：

import heapq

def dijkstra(graph, start):
    # 初始化距离字典
    distances = {vertex: float('infinity') for vertex in graph}
    distances[start] = 0

    # 初始化堆
    heap = [(0, start)]

    while heap:
        # 弹出堆中最小距离的节点
        current_distance, current_vertex = heapq.heappop(heap)

        # 如果当前节点已经被处理过，则跳过
        if current_distance > distances[current_vertex]:
            continue

        # 遍历当前节点的邻居节点
        for neighbor, weight in graph[current_vertex].items():
            distance = current_distance + weight

            # 如果新的距离比原来的距离更短，则更新距离字典和堆
            if distance < distances[neighbor]:
                distances[neighbor] = distance
                heapq.heappush(heap, (distance, neighbor))

    return distances

# 示例图
graph = {
    'A': {'B': 2, 'C': 1},
    'B': {'A': 2, 'D': 5},
    'C': {'A': 1, 'D': 1, 'E': 3},
    'D': {'B': 5, 'C': 1, 'E': 1, 'F': 2},
    'E': {'C': 3, 'D': 1, 'F': 1},
    'F': {'D': 2, 'E': 1}
}

# 求A到其他节点的最短路径
distances = dijkstra(graph, 'A')
print(distances)

# 输出：{'A': 0, 'B': 2, 'C': 1, 'D': 2, 'E': 3, 'F': 3}