RT，已发现问题在 md 数组（md[u][i] 表示从 $u$ 节点向上 $2^i$ 条边的最小值，即 min_dis），但就是不知道错在哪里

#import "iostream"
#import "vector"
#import "algorithm"
#define For(a, b, c) for (int a = b, a##END = c; a <= a##END; ++ a)
#define Fol(a, b, c) for (int a = b, a##END = c; a >= a##END; -- a)
#define id first
#define w second
using namespace std;
const int N = 2.5e5 + 7;
int n, m, k, h[N];

vector<pair<int, int> > g[N], g1[N];
int tmp[N << 1], tot;

int dep[N], dfn[N], fa[N][20], cnt, md[N][20];
void dfs1(int u, int f) {
	dep[u] = dep[f] + 1;
	fa[u][0] = f; dfn[u] = ++ cnt;
	for (auto son : g[u]) if (son.id != f)
		md[son.id][0] = son.w, dfs1(son.id, u);
}
int dp[N]; bool key[N];
void dfs2(int u) {
	dp[u] = 0;
	for (auto son : g1[u]) {
		dfs2(son.id);
		dp[u] += key[son.id] ? son.w : min(dp[son.id], son.w);
	}
}
void init_ST() {
	For (i, 1, 19)
		For (j, 1, n)
			fa[j][i] = fa[fa[j][i - 1]][i - 1],
			md[j][i] = min(md[j][i - 1], md[fa[j][i - 1]][i - 1]);
}
pair<int, int> lca_dis(int x, int y) {
	int ret = 2e9;
	if (dep[x] < dep[y]) x ^= y ^= x ^= y;
	Fol (i, 19, 0)
		if (dep[fa[x][i]] >= dep[y])
			ret = min(ret, md[x][i]), x = fa[x][i];
	if (x == y) return {x, ret};
	Fol (i, 19, 0)
		if (fa[x][i] != fa[y][i])
			ret = min({ret, md[x][i], md[y][i]}),
			x = fa[x][i], y = fa[y][i];
	return {fa[x][0], ret};
}
main() {
	__builtin_memset(md, 0x3f, sizeof md);
//	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	cin >> n;
	For (i, 2, n) {
		int u, v, w; cin >> u >> v >> w;
		g[u].emplace_back(v, w),
		g[v].emplace_back(u, w);
	}
	dfs1(1, 0); init_ST();
	cin >> m;
	For (i, 1, m) {
		cin >> k, ++ k;
		h[1] = 1;
		For (j, 2, k) cin >> h[j], key[h[j]] = 1;
// build:
		tot = 0;
		sort(h + 1, h + 1 + k, [](int x, int y) { return dfn[x] < dfn[y]; });
		For (i, 1, k - 1)
			tmp[++ tot] = h[i], tmp[++ tot] = lca_dis(h[i], h[i + 1]).id;
		tmp[++ tot] = h[k];
		sort(tmp + 1, tmp + 1 + tot, [](int x, int y) { return dfn[x] < dfn[y]; });
		tot = unique(tmp + 1, tmp + 1 + tot) - tmp - 1;
		For (i, 1, tot - 1) {
			const auto lca_ = lca_dis(tmp[i], tmp[i + 1]);
			g1[lca_.id].emplace_back(tmp[i + 1], lca_.w);
			cerr << "(" << lca_.id << ", " << tmp[i + 1] << ") = " << lca_.w << "\n";
		}
// test:
		for (int i = 1; i <= n; ++ i) <%
			cerr << i << ": ";
			for (auto x : g1[i])
				cerr << "(" << x.id << ", " << x.w << "), ";
			cerr << "\n";
		%>
// solve:
		dfs2(1);
		cout << dp[1] << "\n";
// clear:
		For (j, 1, k) key[h[j]] = 0;
		For (j, 1, n) g1[j].clear();
	}
}
/*
for node u, son v:
	v \in KeyNodes:	dp[u] += min(dp[v], dis(u, v))
					dp[u] += dis(u, v)
*/