CSES – Flight Routes Check

#include<bits/stdc++.h>
#define int long long
#define pii pair<int,int>
#define f first
#define s second
#define fastio ios_base::sync_with_stdio(0);
using namespace std;
//declare
const int maxn = 1e5+5;
int n,m;
vector<int> G[maxn], reverse_G[maxn];
bool vis[maxn];
//
void dfs(int cur){
    if(vis[cur]) return;
    vis[cur] = 1;
    for(int adj : G[cur]){
        dfs(adj);
    }
}
void dfs2(int cur){
    if(vis[cur]) return;
    vis[cur] = 1;
    for(int adj : reverse_G[cur]){
        dfs2(adj);
    }
}
void kosaraju(){
    dfs(1);
    for(int i=1;i<=n;i++){
        if(!vis[i]){
            cout<<"NO\n";
            cout<<1<<" "<<i<<"\n";
            return;
        }
        vis[i] = 0;
    }
    dfs2(1);
    for(int i=1;i<=n;i++){
        if(!vis[i]){
            cout<<"NO\n";
            cout<<i<<" "<<1<<"\n";
            return;
        }
    }
    cout<<"YES\n";
    return;
}
signed main(){
    fastio;
    cin>>n>>m;
    for(int i=0;i<m;i++){
        int a,b; cin>>a>>b;
        G[a].push_back(b);
        reverse_G[b].push_back(a);
    }
    kosaraju();
    return 0;
}