题目大意：给你N个点，其中一个点是你当前所在的位置，现在提供两种操作
0 u:从当前点到u点的距离
1 u w：将第u条边的权值改成w

解题思路：树剖裸题，不过这题坑，卡了vector

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int N = 100010;

struct Edge{
    int u, v, dis, next;
    Edge() {}
    Edge(int u, int v, int dis, int next): u(u), v(v), dis(dis), next(next){}
}E[N * 2];

int dep[N], size[N], top[N], son[N], id[N], f[N], head[N];
int n, q, s, idx, tot;
int bit[N];

void dfs1(int u, int fa, int depth) {
    dep[u] = depth; size[u] = 1; son[u] = 0; f[u] = fa;
    for (int i = head[u]; ~i; i = E[i].next) {
        int v = E[i].v;
        if (v == fa) continue;
        dfs1(v, u, depth + 1);
        size[u] += size[v];
        if (size[son[u]] < size[v]) son[u] = v;
    }
} 

void dfs2(int u, int tp) {
    top[u] = tp;
    id[u] = ++idx;
    if (son[u]) dfs2(son[u], tp);

    for (int i = head[u]; ~i; i = E[i].next) {
        int v = E[i].v;
        if (v == f[u] || v == son[u]) continue;
        dfs2(v, v);
    }
}

inline int lowbit(int x) {
    return x & (-x);
}

void add(int x, int w) {
    while (x < N) {
        bit[x] += w;
        x += lowbit(x);
    }
}

int query(int x) {
    int ans = 0;
    while (x) {
        ans += bit[x];
        x -= lowbit(x);
    }
    return ans;
}

int query(int l, int r) {
    return query(r) - query(l - 1);
}

int gao(int u, int v) {
    int tp1 = top[u], tp2 = top[v];
    int ans = 0;
    while (tp1 != tp2) {
        if (dep[tp1] < dep[tp2]) {
            swap(tp1, tp2);
            swap(u, v);
        }
        ans += query(id[tp1], id[u]);
        u = f[tp1];
        tp1 = top[u];
    }
    if (u == v) return ans;
    if (dep[u] > dep[v]) swap(u, v);
    ans += query(id[son[u]], id[v]);
    return ans;
}

void solve() {
    int op, a, b;
    while (q--) {
        scanf("%d", &op);
        if (op == 1) {
            scanf("%d%d", &a, &b);
            a--;
            int tmp = query(id[E[a * 2].u], id[E[a * 2].u]);
            add(id[E[a * 2].u], b - tmp);
        }
        else {
            scanf("%d", &a);
            printf("%d\n", gao(s, a));
            s = a;
        }
    }
}

void AddEdge(int u, int v, int dis) {
    E[tot] = Edge(u, v, dis, head[u]);
    head[u] = tot++;
    E[tot] = Edge(v, u, dis, head[v]);
    head[v] = tot++;
}

void init() {

    memset(bit, 0, sizeof(bit));
    memset(head, -1, sizeof(head));
    idx = tot = 0;

    int u, v, dis;
    for (int i = 1; i < n; i++) {
        scanf("%d%d%d", &u, &v, &dis);
        AddEdge(u, v, dis);
    }

    dfs1(1, 0, 1);
    dfs2(1, 1);

    for (int i = 0; i < tot; i += 2) {
        if (dep[E[i].u] < dep[E[i].v]) swap(E[i].u, E[i].v);
        add(id[E[i].u], E[i].dis);
    }
}

int main() {
    while (scanf("%d%d%d", &n, &q, &s) != EOF) {
        init();
        solve();
    }
    return 0;
}