#include <iostream>
#include <set>
#include <algorithm>
#include <cstring>
using namespace std;
#define int long long
const int N = 1e5 + 5, M = 2e5 + 5, K = 20, INF = 0x3f3f3f3f;
int dfn[N], t[N], h[N], e[M], ne[M], w[M], d[N], dep[N], fa[N][K];
int u, v, idx, n, m, x, res, a, b, c, l, r, ts;
char op;
set<int> dot;
void add(int a, int b, int c)
{
    e[idx] = b, ne[idx] = h[a], w[idx] = c, h[a] = idx++;
}
void dfs(int u, int father)
{
    dfn[u] = ++ts, t[ts] = u, fa[u][0] = father, dep[u] = dep[father] + 1;
    for (int i = 1; i < K; i++)
        fa[u][i] = fa[fa[u][i - 1]][i - 1];
    for (int i = h[u]; ~i; i = ne[i])
    {
        int j = e[i];
        if (j == father)
            continue;
        d[j] = d[u] + w[i], dfs(j, u);
    }
}
int lca(int u, int v)
{
    if (dep[u] < dep[v])
        swap(u, v);
    for (int i = K - 1; ~i; i--)
        if (dep[fa[u][i]] >= dep[v])
            u = fa[u][i];
    if (u == v)
        return u;
    for (int i = K - 1; ~i; i--)
        if (fa[u][i] != fa[v][i])
            u = fa[u][i], v = fa[v][i];
    return fa[u][0];
}
int path(int u, int v)
{
    return d[u] + d[v] - 2 * d[lca(u, v)];
}
signed main()
{
    ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
    cin >> n, dot.insert(-1), dot.insert(INF), memset(h, -1, sizeof(h));
    for (int i = 1; i < n; i++)
        cin >> a >> b >> c, add(a, b, c), add(b, a, c);
    dfs(1, 0);
    cin >> m;
    while (m--)
    {
        cin >> op;
        if (op == '?')
            cout << res / 2 << "\n";
        else if (op == '+')
        {
            cin >> x, dot.insert(dfn[x]);
            auto it1 = lower_bound(dot.begin(), dot.end(), dfn[x]), it2 = it1;
            if (dot.size() > 2)
            {
                r = *(++it1), l = *(--it2);
                if (l == -1)
                    l = *(--(--dot.end()));
                if (r == INF)
                    r = *(++dot.begin());
                u = t[l], v = t[r], res = res - path(u, v) + path(u, x) + path(x, v);
            }
        }
        else
        {
            cin >> x;
            auto it0 = lower_bound(dot.begin(), dot.end(), dfn[x]), it2 = it0, it1 = it0;
            if (dot.size() > 3)
            {
                r = *(++it1), l = *(--it2);
                if (l == -1)
                    l = *(--(--dot.end()));
                if (r == INF)
                    r = *(++dot.begin());
                u = t[l], v = t[r], res = res + path(u, v) - path(u, x) - path(x, v);
            }
            dot.erase(it0);
        }
    }
}

根据进阶指南上思路写的，在ACW只过了4个点，一篇跟蓝书思路一致的题解却可以900多msAC，我是哪里写挂了吗？我不常用set，对迭代器操作不熟