请给出使用Dijkstra算法解决农夫过河问题的代码

好的，农夫过河问题是经典的图论问题，可以使用Dijkstra算法来找到最短路径。这里我们假设有一条河，农夫需要借助渡船每次只能带一定重量的食物过河，每种食物有自己的重量。以下是用Python实现的一个简化版Dijkstra算法：

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
        
        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

# 示例图（这里只是一个简单表示，实际可能更复杂）
graph = {
    'A': {'B': 1},
    'B': {'C': 2, 'D': 5},
    'C': {},
    'D': {'E': 3},
    'E': {}
}

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

for node, path_length in shortest_paths.items():
    print(f"从{start_node}到{node}的最短距离是: {path_length}")