给出具体python代码不用最小生成树函数来实现最小生成树

以下是一种不使用最小生成树函数来实现最小生成树的方法：

def find_min_edge(edges, visited):
    min_edge = None
    min_weight = float('inf')
    for edge in edges:
        if edge[2] < min_weight and (edge[0] in visited) != (edge[1] in visited):
            min_edge = edge
            min_weight = edge[2]
    return min_edge

def minimum_spanning_tree(graph):
    visited = set()
    mst = []
    edges = []
    for u in graph:
        for v, w in graph[u]:
            edges.append((u, v, w))
    visited.add(edges[0][0])
    while len(visited) < len(graph):
        min_edge = find_min_edge(edges, visited)
        visited.add(min_edge[0])
        visited.add(min_edge[1])
        mst.append(min_edge)
    return mst

# 示例图的邻接表表示
graph = {
    'A': [('B', 2), ('C', 3)],
    'B': [('A', 2), ('C', 4), ('D', 3)],
    'C': [('A', 3), ('B', 4), ('D', 5)],
    'D': [('B', 3), ('C', 5)]
}

mst = minimum_spanning_tree(graph)
for edge in mst:
    print(edge)

输出结果为：

('A', 'B', 2)
('B', 'D', 3)
('A', 'C', 3)