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| #include <bits/stdc++.h>
using namespace std;
const int MAXN = 2e5 + 5, MAXE = 4e6 + 5;
struct {
int v, w, nxt, pre;
} edge[MAXE], _edge[MAXE];
int head[MAXN], _head[MAXN], tot, _tot, tail[MAXN], mark[MAXN], size[MAXN], n,
_n, cnt, rt, midedge, maxv;
inline void _add(int u, int v, int w) {
_edge[_tot].v = v, _edge[_tot].w = w, _edge[_tot].nxt = _head[u],
_head[u] = _tot++;
}
inline void add(int u, int v, int w) {
edge[tot].v = v, edge[tot].w = w, edge[tot].nxt = head[u], head[u] = tot++;
}
inline void del(int u, int i) {
if (head[u] == i)
head[u] = edge[i].nxt;
else
edge[edge[i].pre].nxt = edge[i].nxt;
if (tail[u] == i)
tail[u] = edge[i].pre;
else
edge[edge[i].nxt].pre = edge[i].pre;
}
inline void build(int u, int fa) {
int father = 0;
for (int i = _head[u]; ~i; i = _edge[i].nxt) {
int v = _edge[i].v, w = _edge[i].w;
if (v == fa)
continue;
if (father == 0)
add(u, v, w), add(v, u, w), father = u, build(v, u);
else
mark[++n] = 0, add(n, father, 0), add(father, n, 0), father = n,
add(v, father, w), add(father, v, w), build(v, u);
}
}
inline void get_pre() {
memset(tail, -1, sizeof(tail));
for (int i = 1; i <= n; i++)
for (int j = head[i]; ~j; j = edge[j].nxt)
edge[j].pre = tail[i], tail[i] = j;
}
struct point {
int u, dis;
point() {}
point(int _u, int _dis) {
u = _u;
dis = _dis;
}
bool operator<(const point &_A) const { return dis < _A.dis; }
};
struct tree {
int rt, midlen, ans, ls, rs;
priority_queue<point> q;
} t[2 * MAXN];
inline void dfs_size(int u, int fa, int dir) {
_add(u, rt, dir);
if (mark[u])
t[rt].q.push(point(u, dir));
size[u] = 1;
for (int i = head[u]; ~i; i = edge[i].nxt) {
int v = edge[i].v, w = edge[i].w;
if (v == fa)
continue;
dfs_size(v, u, dir + w), size[u] += size[v];
}
}
inline void dfs_midedge(int u, int fa) {
if (max(size[u], size[t[rt].rt] - size[u]) < maxv)
maxv = max(size[u], size[t[rt].rt] - size[u]), midedge = fa;
for (int i = head[u]; ~i; i = edge[i].nxt) {
int v = edge[i].v;
if (i != (fa ^ 1))
dfs_midedge(v, i);
}
}
inline void pushup(int rt) {
t[rt].ans = -1;
for (; !t[rt].q.empty() && mark[t[rt].q.top().u] == 0;)
t[rt].q.pop();
int ls = t[rt].ls, rs = t[rt].rs;
if (ls == 0 && rs == 0) {
if (mark[t[rt].rt])
t[rt].ans = 0;
} else {
if (t[ls].ans > t[rt].ans)
t[rt].ans = t[ls].ans;
if (t[rs].ans > t[rt].ans)
t[rt].ans = t[rs].ans;
if (!t[ls].q.empty() && !t[rs].q.empty())
t[rt].ans =
max(t[rt].ans, t[ls].q.top().dis + t[rs].q.top().dis + t[rt].midlen);
}
}
inline void dfs(int id, int u) {
rt = id, maxv = n, midedge = -1, t[id].rt = u;
dfs_size(u, 0, 0), dfs_midedge(u, -1);
if (~midedge) {
int p1 = edge[midedge].v, p2 = edge[midedge ^ 1].v;
t[id].midlen = edge[midedge].w, t[id].ls = ++cnt, t[id].rs = ++cnt,
del(p1, midedge ^ 1), del(p2, midedge), dfs(t[id].ls, p1),
dfs(t[id].rs, p2);
}
pushup(id);
}
inline void update(int u) {
mark[u] ^= 1;
for (int i = _head[u]; ~i; i = _edge[i].nxt) {
int v = _edge[i].v, w = _edge[i].w;
if (mark[u] == 1)
t[v].q.push(point(u, w));
pushup(v);
}
}
int main() {
memset(_head, -1, sizeof(_head)), scanf("%d", &_n);
for (int i = 1, u, v, w; i < _n; i++)
scanf("%d%d%d", &u, &v, &w), _add(u, v, w), _add(v, u, w);
memset(head, -1, sizeof(head)), n = _n;
for (int i = 1; i <= n; i++)
mark[i] = 1;
build(1, 0), get_pre(), memset(_head, -1, sizeof(_head)), _tot = 0,
dfs(cnt = 1, 1);
char op[2];
int m, x;
scanf("%d", &m);
for (; m; --m) {
scanf("%s", op);
if (op[0] == 'A')
if (t[1].ans == -1)
printf("They have disappeared.\n");
else
printf("%d\n", t[1].ans);
else
scanf("%d", &x), update(x);
}
return 0;
}
|
