Connect cities

#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);
    }

    bool allfound = false;
    vector<bool> visited(n+1, false);
    
    int start = 1;
    while(!allfound) {
        queue<int> q;

        visited[start] = true;
        q.push(start);

        while (!q.empty()) {
            int s = q.front(); q.pop();
            for (auto u : adj[s]) {
                if (visited[u]) continue;
                visited[u] = true;
                q.push(u);
            }
        }

        allfound = true;
        for(int i = start; i <= n; i++) {
            if(!visited[i]) {
                addNodes.push_back(i);
                allfound = false;
                start = i;
                break;
            }
        }
        /*for( int i = 1; i <= n; i++) {
            cout << i << ": " << visited[i] <<endl;
        }*/
    


}

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