[uva] 796 – critical links

#include <iostream>
#include <utility>
#include <vector>
#ifdef LOCAL
#include "stloutput.h"
#endif
#define INF 1000000000

using namespace std;

vector<vector<int>> g;
vector<int> dfs_num, dfs_lo;
vector<pair<int, int>> ans;
int cnt;

int (int s, int t) {
    dfs_num[t] = dfs_lo[t] = cnt++;
    for (auto i : g[t]) {
        if (dfs_num[i] == -1) {
            dfs(t, i);
            if (dfs_lo[i] > dfs_num[t]) {
                pair<int, int> p;
                if (t > i) {
                    p = make_pair(i, t);
                } else {
                    p = make_pair(t, i);
                }
                ans.push_back(p);
            }
            dfs_lo[t] = min(dfs_lo[t], dfs_lo[i]);
        } else if (s != i) {
            dfs_lo[t] = min(dfs_lo[t], dfs_num[i]);
        }
    }
}

int main() {
    int n;
    while (cin >> n) {
        int s, t, k;
        g.clear();
        g.resize(n);
        for (int j = 0; j < n; j++) {
            scanf("%d (%d)", &s, &k);
            for (int i = 0; i < k; i++) {
                cin >> t;
                g[s].push_back(t);
            }
        }
        dfs_num.clear();
        dfs_num.resize(n, -1);
        dfs_lo.clear();
        dfs_lo.resize(n);
        ans.clear();
        cnt = 0;
        for (int i = 0; i < n; i++) {
            if (dfs_num[i] == -1) dfs(-1, i);
        }
        sort(ans.begin(), ans.end());
        printf("%d critical linksn", ans.size());
        for (auto i : ans) {
            printf("%d - %dn", i.first, i.second);
        }
        puts("");
    }
}