题解 | 邮递员送信

void solve() {
    int n, m;
    rd(n, m);
    vector<vector<int>> g(n + 1, vector<int>(n + 1, 1e9));
    for (int i = 1; i <= n; i++) {
        g[i][i] = 0;
    }
    while (m--) {
        int u, v, w;
        rd(u, v, w);
        g[u][v] = w;
    }
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            for (int k = 1; k <= n; k++) {
                if (g[j][k] > g[j][i] + g[i][k]) {
                    g[j][k] = g[j][i] + g[i][k];
                   // print(g[i][j], '\n');
                }
            }
        }
    }
    // rep(i, 1, n) rep(j, 1, n) print(g[i][j], " \n"[j == n]);
    int sm = 0;
    for (int i = 2; i <= n; i++) {
        sm += g[1][i] + g[i][1];
    }
    print(sm);
}