https://ac.nowcoder.com/acm/contest/24872/H

#include<bits/stdc++.h>
using namespace std;
const int N = 2e5 + 5;
typedef long long LL;
#define debug(x) cout << "debug : " << x << endl;

#define int long long

int pre[N], fa[N][22];
int n, m, q;
int sz[N];

struct EDGE {
    int u, v, w;
    bool operator < (const EDGE& a) const {
        return w < a.w;
    }
}edge[N];

vector<int>g[N];
int rt, root[N];
int find(int x) {
    if (x != pre[x]) {
        return pre[x] = find(pre[x]);
    }
    return pre[x];
}
void Kruskal() {
    rt = n;
    sort(edge + 1, edge + 1 + m);
    for (int i = 1; i <= m; ++i) {
        int fx = find(edge[i].u), fy = find(edge[i].v), w = edge[i].w;
        if (fx != fy) {
            ++rt;
            pre[fx] = pre[fy] = pre[rt] = rt;
            root[rt] = w;
            g[rt].push_back(fx);
            g[rt].push_back(fy);
        }
    }
}

void dfs(int u, int fat) {
    fa[u][0] = fat;
    for (int i = 1; i <= 20; ++i) {
        fa[u][i] = fa[fa[u][i - 1]][i - 1];
    }
    for (int i = 0; i < g[u].size(); ++i) {
        int v = g[u][i];
        dfs(v, u);
        sz[u] += sz[v];
    }
}

void solve() {
    cin >> n >> m >> q;
    for (int i = 1; i <= n + m; ++i) {
        pre[i] = i;
    }
    for (int i = 1; i <= n; ++i) {
        cin >> sz[i];
    }
    for (int i = 1; i <= m; ++i) {
        int u, v, w; cin >> u >> v >> w;
        edge[i] = {u, v, w};
    }

    Kruskal();
    dfs(rt, 0);

    while (q--) {
        int u, s; cin >> u >> s;
        int now = s + sz[u];
        while (u != rt) {
            int x = u;
            for (int i = 20; i >= 0; --i) {
                if (fa[u][i] && root[fa[u][i]] <= now) {
                    u = fa[u][i];
                }
            }
            if (x == u) break;
            now = sz[u] + s;
        }
        cout << now << "\n";
    }
}

signed main() {
    ios::sync_with_stdio(0); cin.tie(0);
#ifdef LOCAL
    freopen("../in", "r", stdin);
//  freopen("../out", "w", stdout);
#endif
    int T = 1;
//  cin >> T;
//  scanf("%d", &T);
    while (T--) {
        solve();
    }

}