Submission #1324159

#	Time	Username	Problem	Language	Result	Execution time	Memory
1324159		mduc209	Potemkin cycle (CEOI15_indcyc)	C++20	20 / 100	1094 ms	1892 KiB

indcyc

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

//#define int long long

const int N = 1005;

int n , r;
bool f[N][N];
vector<int> adj[N];

int vis[N], par[N], cnt = 0;

void solve(){
    cin >> n >> r;
    for(int i = 1; i <= r; ++i){
        int u , v; cin >> u >> v;
        f[u][v] = f[v][u] = 1;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    for(int u = 1; u <= n; ++u){
        for(int v : adj[u]){
            cnt++;
            vis[u] = cnt;
            vis[v] = cnt;
            for(int x : adj[u]){
                if(f[v][x]) vis[x] = cnt;
            }
            queue<int> q;
            q.push(v);
            par[v] = -1;
            int res = -1;
            while(q.size()){
                int curr = q.front(); q.pop();
                if(curr != v && f[u][curr]){
                    res = curr;
                    break;
                }
                for(int nxt : adj[curr]){
                    if(vis[nxt] != cnt){
                        vis[nxt] = cnt;
                        par[nxt] = curr;
                        q.push(nxt);
                    }
                }
            }
            if(res != -1){
                vector<int> vec;
                vec.push_back(u);
                int curr = res;
                while(curr != -1){
                    vec.push_back(curr);
                    curr = par[curr];
                }
                for(int x : vec) cout << x << ' ';
                cout << '\n';
                return;
            }
        }
    }
    cout << "NO\n";
}

signed main(){
    #define name "hi"
    if(fopen(name ".inp", "r")){
        freopen(name ".inp", "r", stdin);
        freopen(name ".out" , "w", stdout);
    }
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int t = 1;
    // cin >> t;
    while(t--) solve();
}

Compilation message (stderr)

indcyc.cpp: In function 'int main()':
indcyc.cpp:68:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   68 |         freopen(name ".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
indcyc.cpp:69:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |         freopen(name ".out" , "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

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