python中dijkstra算法代码

以下是Python中实现Dijkstra算法的代码：

import sys

def dijkstra(graph, source):
    distance = {node: sys.maxsize for node in graph}
    distance[source] = 0
    visited = set()

    while len(visited) < len(graph):
        node = min((dist, node) for node, dist in distance.items() if node not in visited)[1]
        visited.add(node)

        for neighbor, weight in graph[node].items():
            new_distance = distance[node] + weight
            if new_distance < distance[neighbor]:
                distance[neighbor] = new_distance

    return distance

# 示例图的邻接矩阵表示
graph = {
    'A': {'B': 3, 'C': 4, 'D': 7},
    'B': {'C': 1, 'F': 5},
    'C': {'F': 6, 'D': 2},
    'D': {'E': 3, 'G': 6},
    'E': {'G': 3, 'H': 4},
    'F': {'E': 1, 'H': 8},
    'G': {'H': 2},
    'H': {'G': 2}
}

source = 'A'
distances = dijkstra(graph, source)
print(distances)