Connect cities

input/code.cpp: In function 'int main()':
input/code.cpp:40:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   40 |     for (int i = 1; i < components.size(); i++) {
      |                     ~~^~~~~~~~~~~~~~~~~~~

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

const int MAXN = 100005;

vector<int> adj[MAXN];
bool visited[MAXN];

void dfs(int node) {
    visited[node] = true;
    for (int neighbor : adj[node]) {
        if (!visited[neighbor]) {
            dfs(neighbor);
        }
    }
}

int main() {
    int n, m;
    cin >> n >> m;

    for (int i = 0; i < m; i++) {
        int a, b;
        cin >> a >> b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }

    vector<int> components;
    for (int i = 1; i <= n; i++) {
        if (!visited[i]) {
            components.push_back(i);
            dfs(i);
        }
    }

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

    return 0;
}

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