EC_P - Critical Edges

Problem Link

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

vector<int> v[701];
vector<pair<int, int>> res;
int in[701], low[701], parent[701];
bool visited[701];
int n, m, a, b, test;
int value = 0;
bool isBridge;

void dfs(int s)
{
visited[s] = true;
int d;
low[s] = in[s] = ++value;

for(int i = 0; i < v[s].size(); i++)
{
d = v[s][i];
if(!visited[d])
{
parent[d] = s;
dfs(d);

low[s] = min(low[s], low[d]);

if(low[d] > in[s])
{
isBridge = true;
if(s < d) {
res.push_back(make_pair(s, d));
}
else
res.push_back(make_pair(d, s));
}
}
else if(d != parent[s])
{
low[s] = min(low[s], in[d]);
}

}
}

int main()
{
cin >> test;
for(int i = 1; i <= test; i++)
{
isBridge = false;
value = 0;
for(int j = 0; j <= 700; j++)
{
visited[j] = false;
parent[j] = j;
v[j].clear();
}
res.clear();

cin >> n >> m;
while(m--)
{
cin >> a >> b;
v[a].push_back(b);
v[b].push_back(a);
}

dfs(1);
cout << "Caso #" << i << endl;

if(!isBridge)
{
cout << "Sin bloqueos\n";
}
else
{
int size = res.size();
sort(res.begin(), res.end());
cout << size << endl;
for(int j = 0; j < size; j++)
{
cout << res[j].first << " " << res[j].second << endl;
}
}
}
}