提出 #65446693

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ソースコード 拡げる

#include<bits/stdc++.h>
using namespace std;
#define IOS ios_base::sync_with_stdio(false);cin.tie(nullptr)
#define INF 0x7fffffff
#define inf 0x3f3f3f3f
#define endl '\n'
#define int long long
#define PII pair<int,int>
#define mod 998244353
const int MOD=1e9+7;
const int N=1e5+10;
int read() {char act = 0;int f = 1, x= 0;while (act = getchar(), act < '0' && act != '-');if (act == '-') f = -1, act = getchar();x = act - '0';while (act = getchar(), act >= '0') x = x * 10 + act - '0';return x * f;}
vector<int>g[200010];
int du[200010];
bool f[200010];
void solve(){
    int n,m;
    cin>>n>>m;
    while(m--){
        int u,v;
        cin>>u>>v;
        g[u].push_back(v);
        g[v].push_back(u);
        du[u]++;
        du[v]++;
    }
    for(int i=1;i<=n;i++){
        if(du[i]!=2){
            cout<<"No"<<endl;
            return;
        }
    }
    queue<int>q;
    q.push(1);
    f[1]=true;
    int sumcnt=0;
    while(q.size()){
        int tt=q.front();
        q.pop();
        sumcnt++;
        for(auto i:g[tt]){
            if(!f[i]){
                f[i]=true;
                q.push(i);
            }
        }
    }
    if(sumcnt==n)cout<<"Yes"<<endl;
    else cout<<"No"<<endl;
}
signed main()
{
    IOS;
    int t=1;
    //cin>>t;
    while(t--){
        solve();
    }

    return 0;
}

提出情報

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