BFS.cpp

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

template <class T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

#define int long long int
#define pb push_back
#define pi pair<int, int>
#define pii pair<int, pi>
#define fir first
#define sec second
#define DEBUG 1
#define MAXN 1001
#define mod 1000000007

int n, m;
vector<int> adj[MAXN];
bool visited[MAXN];

void bfs(int s)
{
  queue<int> q;
  q.push(s);
  while (!q.empty())
  {
    int v = q.front();
    q.pop();
    if (visited[v])
      continue;
    visited[v] = true;
    for (auto const &u : adj[v])
      if (!visited[u])
        q.push(u);
  }
}
signed main()
{
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n >> m;
  for (int i = 0; i < m; i++)
  {
    int a, b, c;
    cin >> a >> b >> c;
    a--, b--;
    adj[a].pb(b);
    adj[b].pb(a);
  }
  bfs(0);
}