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| #include <bits/stdc++.h>
using namespace std;
#define lson(u) node[u].l
#define rson(u) node[u].r
#define sum(u) node[u].sum
#define tag(u) node[u].tag
const int maxn = 500005;
struct Node {
int sum, l, r, tag;
}node[maxn * 3];
int R, cnt;
void build(int& u, int l, int r) {
u = ++cnt;
tag(u) = -1;
if (l == r) return;
int mid = (l + r) >> 1;
build(lson(u), l, mid);
build(rson(u), mid + 1, r);
}
inline void pushdown(int u, int l, int r) {
int mid = (l + r) >> 1;
int llen = mid - l + 1, rlen = r - mid;
if (tag(u) != -1) {
sum(lson(u)) = llen * tag(u);
sum(rson(u)) = rlen * tag(u);
tag(lson(u)) = tag(u);
tag(rson(u)) = tag(u);
tag(u) = -1;
}
}
void modify(int u, int l, int r, int ql, int qr, int val) {
if (ql <= l && r <= qr) {
sum(u) = (r - l + 1) * val;
tag(u) = val;
return;
}
pushdown(u, l, r);
int mid = (l + r) >> 1;
if (ql <= mid) modify(lson(u), l, mid, ql, qr, val);
if (mid < qr) modify(rson(u), mid + 1, r, ql, qr, val);
sum(u) = sum(lson(u)) + sum(rson(u));
}
int query(int u, int l, int r, int ql, int qr) {
if (ql <= l && r <= qr)
return sum(u);
pushdown(u, l, r);
int mid = (l + r) >> 1, ret = 0;
if (ql <= mid) ret += query(lson(u), l, mid, ql, qr);
if (mid < qr) ret += query(rson(u), mid + 1, r, ql, qr);
return ret;
}
int N, Q, K, root;
vector<int> G[maxn];
int f[maxn][20], dep[maxn];
int dfn[maxn], dfn_idx, size[maxn];
int p[maxn];
void dfs(int u, int fa) {
size[u] = 1;
dfn[u] = ++dfn_idx;
dep[u] = dep[fa] + 1;
f[u][0] = fa;
for (int i = 1; i <= 19; ++i)
f[u][i] = f[f[u][i - 1]][i - 1];
for (vector<int>::iterator it = G[u].begin(); it != G[u].end(); it++) {
int v = *it;
if (v == fa) continue;
dfs(v, u);
size[u] += size[v];
}
}
inline int Lca(int u, int v) {
if (dep[u] < dep[v]) swap(u, v);
for (int i = 19; ~i; --i)
if (dep[f[u][i]] >= dep[v]) u = f[u][i];
if (u == v) return u;
for (int i = 19; ~i; --i)
if (f[u][i] != f[v][i]) u = f[u][i], v = f[v][i];
return f[u][0];
}
inline int Jump(int u, int d) {
for (int i = 19; ~i; --i)
if (d - (1 << i) >= 0) u = f[u][i], d -= (1 << i);
return u;
}
int main() {
scanf("%d%d", &N, &Q);
for (register int i = 1; i < N; ++i) {
int u, v;
scanf("%d%d", &u, &v);
G[u].push_back(v);
G[v].push_back(u);
}
dfs(1, 0);
build(R, 1, N);
while (Q--) {
scanf("%d", &K);
for (register int i = 1; i <= K; ++i)
scanf("%d", &p[i]);
root = p[1];
for (register int i = 2; i <= K; ++i) {
int t = p[i];
int lca = Lca(root, t);
int dis = dep[t] + dep[root] - 2 * dep[lca];
if (dis & 1) dis = (dis >> 1);
else dis = (dis >> 1) - 1;
int dis_root = dep[root] - dep[lca];
int dis_t = dep[t] - dep[lca];
int u = 0;
if (dis <= dis_t) {
u = Jump(t, dis);
} else u = Jump(root, dis_root + dis_t - dis);
if (Lca(root, u) != u)
modify(R, 1, N, dfn[u], dfn[u] + size[u] - 1, 1);
else {
int v = Jump(root, dep[root] - dep[u] - 1);
if (dfn[v] - 1 >= 1) modify(R, 1, N, 1, dfn[v] - 1, 1);
if (dfn[v] + size[v] <= N) modify(R, 1, N, dfn[v] + size[v], N, 1);
}
}
printf("%d\n", N - query(R, 1, N, 1, N));
modify(R, 1, N, 1, N, 0);
}
return 0;
}
|