Connect cities

input/code.cpp: In function 'int main()':
input/code.cpp:46:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   46 |     for (int i = 1; i < rep.size(); ++i) {
      |                     ~~^~~~~~~~~~~~

#include <iostream>
#include <vector>
#include <algorithm>
#include <bits/stdc++.h>
using namespace std;


void dfs(int node, const vector<vector<int>>& roads, vector<bool>& visited) {
    visited[node] = true;
    for (int neighbor : roads[node]) {
        if (!visited[neighbor]) {
            dfs(neighbor, roads, visited);
        }
    }
}

int main() {
    
    int n, m;

    cin >> n >> m;

    vector< vector<int> > roads = vector<vector<int> >(n+1);
    for (int i = 0; i < m; ++i)
    {
        int aux1, aux2;

        cin >> aux1 >> aux2;

        roads[aux1].push_back(aux2);
        roads[aux2].push_back(aux1);
    }

    vector<bool> visited(n + 1, false);
    vector<int> rep;

    for (int i = 1; i <= n; ++i) {
        if (!visited[i]) {
            rep.push_back(i);
            dfs(i, roads, visited);
        }
    }

    int k = rep.size() - 1;
    cout << k << endl;
    for (int i = 1; i < rep.size(); ++i) {
        cout << rep[i - 1] << " " << rep[i] << endl;
    }

}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED