Submission #1116092

#	Time	Username	Problem	Language	Result	Execution time	Memory
1116092		vjudge1	Potemkin cycle (CEOI15_indcyc)	C++17	60 / 100	15 ms	2640 KiB

indcyc

#include <bits/stdc++.h>
#define pb push_back
#define spc << " " <<
#define endl "\n"
#define all(x) x.begin(), x.end()
#define int long long
#define ii pair<int, int>
#define vi vector<int>
#define vii vector<ii>
#define st first
#define nd second
#define mid (l+r)/2
#define inf 1e15
#define MOD 998244353
#define MX 1005
using namespace std;

vi edges[MX], ans;
bitset<MX> adj[MX];
int vis[MX], revis[MX];
int tim=0, last=-1;
int dfs(int node, int par){
    //cerr << node+1 spc par+1 << endl;
    vis[node]=++tim;
    revis[tim]=node;
    int can=-1;
    for(auto i:edges[node]){
        if(i==par) continue;
        if(vis[i]>0){
            auto dont=adj[node];
            dont&=adj[par];
            if(node!=0 && dont[i]==1) continue;
            if(can==-1 || vis[i]>vis[can]){
                auto wow=adj[i];
                for(int j=vis[i]; j<vis[node]; j++){
                    wow&=adj[revis[j]];
                }
                if(wow[node]==0){
                    can=i;
                }
            }
        }
    }
    if(can!=-1){
        ans.pb(node+1);
        last=node;
        return can;
    }
    for(auto i:edges[node]){
        if(i==par) continue;
        if(vis[i]!=0) continue;
        int res=dfs(i, node);
        if(res==-2) return -2;
        if(res!=-1){
            if(node==res){
                ans.pb(node+1);
                return -2;
            }
            auto dont=adj[node];
            dont&=adj[last];
            if(dont[par]==0){
                ans.pb(node+1);
                last=node;
            }
            return res;
        }
    }
    vis[node]=-1;
    return -1;
}

int dfs2(int node, int par){
    vis[node]=++tim;
    int can=-1;
    for(auto i:edges[node]){
        if(i==par) continue;
        if(vis[i]>0){
            if(can==-1 || vis[i]>vis[can]) can=i;
        }
    }
    if(can!=-1){
        cout << node+1 << " ";
        return can;
    }
    for(auto i:edges[node]){
        if(i==par) continue;
        if(vis[i]!=0) continue;
        auto dont=adj[node];
        dont&=adj[par];
        if(node!=par && dont[i]==1) continue;
        int res=dfs2(i, node);
        if(res==-2) return -2;
        if(res!=-1){
            cout << node+1 << " ";
            if(node!=res) return res;
            else return -2;
        }
    }
    vis[node]=-1;
    return -1;
}

void solve(){
    int n,m; cin >> n >> m;
    for(int i=0; i<n; i++){
        adj[MX].reset();
        vis[i]=0;
    }
    for(int i=1; i<=m; i++){
        int a,b; cin >> a >> b; a--, b--;
        edges[a].pb(b);
        edges[b].pb(a);
        adj[a].set(b);
        adj[b].set(a);
    }
    if(dfs2(0,0)!=-1){
        for(auto i:ans) cout << i << " ";
        return;
    }
    memset(vis, 0, sizeof(vis));
    tim=0;
    ans.clear();
    if(dfs(0,0)==-1 || ans.size()<4) cout << "no" << endl;
    else for(auto i:ans) cout << i << " ";
}


signed main(){
    ios_base::sync_with_stdio(false);cin.tie(0);
    #ifdef Local
    freopen("in","r",stdin);
    freopen("out","w",stdout);
    /*#else
    freopen("","r",stdin);
    freopen("","w",stdout);*/
    #endif

    int t=1;
    //cin >> t;
    while(t--) solve();
}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 10 / 10
• Subtask 9: 0 / 10
• Subtask 10: 10 / 10