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| #include <iostream>
#include <queue>
#define maxn 100010
#define INF 1000000000
using namespace std;
int n, m, col[maxn];
struct Edge {
int to, next;
} e[maxn * 2]; int c1, head[maxn];
inline void add_edge(int u, int v) {
e[c1].to = v; e[c1].next = head[u]; head[u] = c1++;
}
int id[maxn * 2], in[maxn], dep[maxn];
void dfs(int u, int fa) {
static int cnt = 0;
id[++cnt] = u; in[u] = cnt;
for (int i = head[u]; ~i; i = e[i].next) {
int v = e[i].to; if (v == fa) continue;
dep[v] = dep[u] + 1; dfs(v, u); id[++cnt] = u;
}
}
inline int st_min(int l, int r) { return in[l] < in[r] ? l : r; }
int st[maxn * 2][21], Log[maxn * 2];
void init_st(int n) { Log[0] = -1;
for (int i = 1; i <= n; ++i) Log[i] = Log[i >> 1] + 1;
for (int i = 1; i <= n; ++i) st[i][0] = id[i];
for (int j = 1; j <= 20; ++j)
for (int i = 1; i + (1 << j) - 1 <= n; ++i)
st[i][j] = st_min(st[i][j - 1], st[i + (1 << j - 1)][j - 1]);
}
inline int get_lca(int l, int r) {
l = in[l]; r = in[r]; if (l > r) swap(l, r);
int k = Log[r - l + 1];
return st_min(st[l][k], st[r - (1 << k) + 1][k]);
}
inline int D(int x, int y) { return dep[x] + dep[y] - 2 * dep[get_lca(x, y)]; }
struct Heap {
priority_queue<int> add, del;
inline void push(int x) { add.push(x); }
inline void erase(int x) { del.push(x); }
inline int top() {
while (!del.empty() && del.top() == add.top()) del.pop(), add.pop();
return add.top();
}
inline int sectop() {
int t1 = top(); pop();
int t2 = top();
return push(t1), t2;
}
inline void pop() {
while (!del.empty() && del.top() == add.top()) del.pop(), add.pop();
add.pop();
}
inline bool empty() { return add.size() - del.size() == 0; }
inline int size() { return add.size() - del.size(); }
} h[maxn * 2], ans;
bool vis[maxn];
namespace Calc_sz {
int f[maxn], sz[maxn];
int sum, rt;
void init() { f[rt = 0] = INF; }
void dfs_sz(int u, int fa) {
sz[u] = 1;
for (int i = head[u]; ~i; i = e[i].next) {
int v = e[i].to; if (v == fa || vis[v]) continue;
dfs_sz(v, u); sz[u] += sz[v];
}
}
void dfs(int u, int fa) {
f[u] = 0;
for (int i = head[u]; ~i; i = e[i].next) {
int v = e[i].to; if (v == fa || vis[v]) continue;
dfs(v, u); f[u] = max(f[u], sz[v]);
} f[u] = max(f[u], sum - sz[u]);
if (f[u] < f[rt]) rt = u;
}
inline int get_rt(int u) {
rt = 0; dfs_sz(u, 0); sum = sz[u];
dfs(u, 0); return rt;
}
}
int fa[maxn];
void divide(int u) {
vis[u] = 1;
for (int i = head[u]; ~i; i = e[i].next) {
int v = e[i].to; if (vis[v]) continue;
v = Calc_sz::get_rt(v); fa[v] = u; divide(v);
}
}
inline void add(Heap &t) {
if (t.size() > 1) ans.push(t.top() + t.sectop());
}
inline void del(Heap &t) {
if (t.size() > 1) ans.erase(t.top() + t.sectop());
}
int tot;
void update(int u, int opt) {
int x = u; tot += opt;
del(h[u]); opt == 1 ? h[u].push(0) : h[u].erase(0); add(h[u]);
while (fa[u]) {
del(h[fa[u]]);
if (h[u + n].size()) h[fa[u]].erase(h[u + n].top());
opt == 1 ? h[u + n].push(D(x, fa[u])) : h[u + n].erase(D(x, fa[u]));
if (h[u + n].size()) h[fa[u]].push(h[u + n].top());
add(h[fa[u]]);
u = fa[u];
}
}
inline void solve_1() {
int x; cin >> x;
if (col[x]) update(x, -1);
else update(x, 1);
col[x] ^= 1;
}
inline void solve_2() {
if (tot < 2) cout << tot - 1 << "\n";
else cout << ans.top() << "\n";
}
int main() { fill(head, head + maxn, -1);
ios::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
cin >> n;
for (int i = 1; i < n; ++i) {
int x, y; cin >> x >> y;
add_edge(x, y); add_edge(y, x);
} dep[1] = 1; dfs(1, 0); init_st(2 * n - 1);
Calc_sz::init(); divide(Calc_sz::get_rt(1));
for (int i = 1; i <= n; ++i) col[i] = 1, update(i, 1);
cin >> m;
for (int i = 1; i <= m; ++i) {
char s[3]; cin >> s + 1;
if (s[1] == 'C') solve_1();
else solve_2();
}
return 0;
}
|