Connect cities

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define die(x) return cout << x << endl, 0
#define all(o) o.begin(), o.end()
#define endl '\n'
#define IOS ios::sync_with_stdio(0), cin.tie(0)
#define FILE freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout)
#define SZ(x) ((int)(x).size())
typedef long double ld;
typedef long long ll;
int gcd(int x,int y){ return (!y ? x : gcd(y, x%y)); }
int to_int(string sconvert){stringstream geek(sconvert);int xconvert = 0; geek >> xconvert; return xconvert;}
const int MAXN=200000+30,MAX_LOG=40,INF=1e18+10,MOD=1e9+7;
const double PI = acos(-1);
int mod(int x) { return (x % MOD + MOD) % MOD; }
int power(int x,int y){
    if(y==0)return 1;
    int c=power(x,y/2);
    c=(c*c)%MOD;
    if(y%2)c=(c*x)%MOD;
    return c;
}

int n, t;
vector<int> g[MAXN];
int visited[MAXN];

vector<pair<int,int>> edges;
void dfs(int v){
    visited[v]=1;
    for(int u:g[v]){
        if(!visited[u])dfs(u);
    }
}


int MAIN(){
    int n, m;
    cin>>n>>m;
 
    for(int i=0;i<m;i++){
        int u, v;
        cin>>u>>v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    int last_component=0;
    for(int i=1;i<=n;i++){
        if(!visited[i]){
            dfs(i);
            if(last_component){
                edges.push_back({last_component, i});
                last_component=i;
            }
            else last_component=i;
            
        }
    }

    cout<<edges.size()<<endl;
    for(auto e:edges){
        cout<<e.first<<" "<<e.second<<endl;
    }
    return 0;
}
int32_t main(){
    IOS;
    int t=1;
    // cin>>t;
    while(t--)MAIN();
    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