Submission #65434827

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Source Code Expand

#include <bits/stdc++.h>
 
using namespace std;

const int MOD=1e9+7;









int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n,m;
	
	cin>>n>>m;
	
	vector<vector<int>> gr(n+1);
	if(n!=m){
		cout<<"No";
		return 0; 
	}
	
	for(int i=0; i<m; i++){
		int x,y;
		cin>>x>>y;
		gr[x].push_back(y);
		gr[y].push_back(x);
		
		
	}
	
	queue<int> q;
	q.push(1);
	int cc=0;
	vector<int> vis(n+1);
	vis[1]=1;
	while(q.size()){
		int cur=q.front();
		q.pop();
		cc++;
		for(int y:gr[cur]){
			if(!vis[y]){
				vis[y]=1;
				q.push(y);
				
			}
		}
	}
	
	if(cc!=n){
		cout<<"No";
		return 0;
	}
	
	for(int i=1; i<=n; i++){
		if(gr[i].size()!=2){
			cout<<"No";
			return 0;
		}
	}
	
	
	
	
	
	cout<<"Yes";
	
	
    return 0;
}

Submission Info

Judge Result