Connect cities

input/code.cpp: In function 'int main()':
input/code.cpp:48:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   48 |     for(int i = 0; i < addNodes.size(); i++) {
      |                    ~~^~~~~~~~~~~~~~~~~

#include <iostream>
#include <algorithm>
#include <queue>

using namespace std;

int main() {
    int n, m;
    cin >> n >> m;
    vector<vector<int>> adj(n+1);
    vector<int> addNodes;

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

    while(true) {
        queue<int> q;
    bool visited[n];
    int distance[n];

    visited[1] = true;
    distance[1] = 0;
    q.push(1);
    while (!q.empty()) {
        int s = q.front(); q.pop();
        // process node s
        for (auto u : adj[s]) {
            if (visited[u]) continue;
            visited[u] = true;
            distance[u] = distance[s]+1;
            q.push(u);
        }
    }

    for(int i = 1; i <= n; i++) {
        if(!visited[i]) {
            adj[1].push_back(i);
            adj[i].push_back(1);
            addNodes.push_back(i);
            break;
        }
    }

    for(int i = 0; i < addNodes.size(); i++) {
       cout << addNodes[i] << " " << 1 << endl;
    }
    return 0;


}
}

Test 1

Verdict: WRONG ANSWER

Test 2

Verdict: WRONG ANSWER

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER