迪杰斯特拉算法代码模板

迪杰斯特拉(Dijkstra's Algorithm)是一种用于寻找图中两个节点之间最短路径的经典算法，它通常用于解决单源最短路径问题。以下是迪杰斯特拉算法的基本Python代码模板：

import heapq

def dijkstra(graph, start):
    distances = {node: float('infinity') for node in graph}
    distances[start] = 0
    queue = [(0, start)]
    
    while queue:
        current_distance, current_node = heapq.heappop(queue)
        
        if current_distance > distances[current_node]:
            continue  # 如果当前距离更大，则跳过
        
        for neighbor, weight in graph[current_node].items():
            distance = current_distance + weight
            
            if distance < distances[neighbor]:
                distances[neighbor] = distance
                heapq.heappush(queue, (distance, neighbor))
                
    return distances

# 示例用法：
graph = {
    'A': {'B': 5, 'C': 1},
    'B': {'A': 5, 'D': 2},
    'C': {'A': 1, 'D': 4},
    'D': {'B': 2, 'C': 4, 'E': 8},
    'E': {'D': 8}
}

start_node = 'A'
shortest_distances = dijkstra(graph, start_node)

print("Shortest distances from {}:".format(start_node))
for node, dist in shortest_distances.items():
    print(f"{node}: {dist} steps")