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| #include <iostream>
#include <cstdio>
#include <cstring>
#include <set>
#include <queue>
#include <algorithm>
#include <cmath>
using namespace std;
typedef long long ll;
const int Maxn = 2e5+5;
int Next[Maxn], head[Maxn], ver[Maxn], edge[Maxn], dfn[Maxn], f[Maxn][30], d[Maxn], a[Maxn];
int x, y, z, n, m, tot, t;
ll dis[Maxn], ans;
char ch[5];
void bfs()
{
queue <int> q;
q.push(1); d[1] = 1;
while(q.size())
{
int x = q.front(); q.pop();
for(int i = head[x]; i; i = Next[i])
{
int y = ver[i]; if(d[y]) continue;
d[y] = d[x] + 1; q.push(y);
f[y][0] = x; dis[y] = dis[x] + edge[i];
for(int j = 1; j <= t; j++){
f[y][j] = f[f[y][j-1]][j-1];
}
}
}
}
int cnt;
void dfs(int x)
{
dfn[x] = ++cnt; a[cnt] = x;
for(int i = head[x]; i; i = Next[i])
{
int y = ver[i];
if(dfn[y]) continue;
dfs(y);
}
}
void add(int x, int y, int z)
{
ver[++tot] = y; Next[tot] = head[x];
head[x] = tot; edge[tot] = z;
}
int lca(int x, int y)
{
if(d[x] > d[y]) swap(x, y);
for(int i = t; i >= 0; i--){
if(d[f[y][i]] >= d[x]) y = f[y][i];
}
if(x == y) return x;
for(int i = t; i >= 0; i--)
{
if(f[x][i] != f[y][i]) x = f[x][i], y = f[y][i];
}
return f[x][0];
}
ll path(int x, int y)
{
return dis[x] + dis[y] - 2 * dis[lca(x, y)];
}
set <int> s;
typedef set <int> :: iterator It;
It it;
It L(It it)
{
if(it == s.begin()) return --s.end();
return --it;
}
It R(It it)
{
if(it == --s.end()) return s.begin();
return ++it;
}
int main()
{
scanf("%d", &n);
t = (int)(log(n) / log(2)) + 1;
for(int i = 1; i < n; i++)
{
scanf("%d%d%d", &x, &y, &z);
add(x, y, z);
add(y, x, z);
}
dfs(1);
bfs();
scanf("%d", &m);
for(int i = 1; i <= m; i++)
{
scanf("%s", ch);
if(ch[0] == '+')
{
scanf("%d", &x);
if(s.size())
{
it = s.upper_bound(dfn[x]);
if(it == s.end()) it = s.begin();
int l = *L(it), r = *it;
ans += path(a[l], x) + path(x, a[r]) - path(a[l], a[r]);
}
s.insert(dfn[x]);
}
else if(ch[0] == '-')
{
scanf("%d", &x);
it = s.find(dfn[x]);
int l = *L(it), r = *R(it);
ans -= path(x, a[l]) + path(x, a[r]) - path(a[l], a[r]);
s.erase(dfn[x]);
}
else
{
printf("%lld\n", ans/2);
}
}
return 0;
}
|
