python求直径最小生成树

以下是Python求直径最小生成树的步骤：
1. 首先，需要使用Kruskal算法来生成最小生成树。
2. 然后，需要对最小生成树进行遍历，找到最长的边，即为直径。
3. 最后，输出直径和最小生成树。

下面是Python代码示例：

# 定义边的类
class Edge:
    def __init__(self, u, v, w):
        self.u = u
        self.v = v
        self.w = w

# 定义并查集类
class UnionFind:
    def __init__(self, n):
        self.parent = list(range(n))
        self.rank = [0] * n

    def find(self, x):
        if self.parent[x] != x:
            self.parent[x] = self.find(self.parent[x])
        return self.parent[x]

    def union(self, x, y):
        px, py = self.find(x), self.find(y)
        if px == py:
            return False
        if self.rank[px] < self.rank[py]:
            px, py = py, px
        self.parent[py] = px
        if self.rank[px] == self.rank[py]:
            self.rank[px] += 1
        return True

# 定义Kruskal算法函数
def kruskal(n, edges):
    uf = UnionFind(n)
    edges.sort(key=lambda e: e.w)
    res = []
    for e in edges:
        if uf.union(e.u, e.v):
            res.append(e)
        if len(res) == n - 1:
            break
    return res

# 定义求直径函数
def diameter(n, edges):
    mst = kruskal(n, edges)
    dist = [-1] * n
    dist[mst[0].u] = 0
    q = [mst[0].u]
    while q:
        u = q.pop(0)
        for e in mst:
            if e.u == u and dist[e.v] == -1:
                dist[e.v] = dist[u] + e.w
                q.append(e.v)
            elif e.v == u and dist[e.u] == -1:
                dist[e.u] = dist[u] + e.w
                q.append(e.u)
    u = max(range(n), key=lambda i: dist[i])
    dist = [-1] * n
    dist[u] = 0
    q = [u]
    while q:
        u = q.pop(0)
        for e in mst:
            if e.u == u and dist[e.v] == -1:
                dist[e.v] = dist[u] + e.w
                q.append(e.v)
            elif e.v == u and dist[e.u] == -1:
                dist[e.u] = dist[u] + e.w
                q.append(e.u)
    return max(dist)

# 测试
n = 5
edges = [Edge(0, 1, 1), Edge(0, 2, 2), Edge(0, 3, 3), Edge(0, 4, 4), Edge(1, 2, 5), Edge(1, 3, 6), Edge(1, 4, 7), Edge(2, 3, 8), Edge(2, 4, 9), Edge(3, 4, 10)]
print("最小生成树：", kruskal(n, edges))
print("直径：", diameter(n, edges))