Submission #1069089

#	Time	Username	Problem	Language	Result	Execution time	Memory
1069089		APROHACK	Potemkin cycle (CEOI15_indcyc)	C++17	20 / 100	10 ms	2396 KiB

indcyc

#include<bits/stdc++.h>
#define ll long long
#define pb push_back
#define ff first
#define ss second
using namespace std;
const int N = 1003, R = 100005;
int n, r;
vector<int>adj[N];
vector<int>ans;
vector<pair<int, int> > backedges[N];
int deep[N];
short vis[N];
const int unvisited = -1;
const int visited = 0;
const int past = 1;

void dfs(int u, int parent, int d){
    deep[u] = d;
    vis[u] = visited;
    for(auto v : adj[u]){
        if(v == parent)continue;
        if(vis[v] == unvisited){
            dfs(v, u, d + 1);
        }else if(vis[v] == past)continue;
        else{
            backedges[u].pb({deep[v], v});
        }
    }
    vis[u] = past;
}

vector<int>stk;

bool respond(int u, int parent, int deepest){
    vis[u] = visited;
    stk.pb(u);
    //sort(backedges[u].rbegin(), backedges[u].rend());
    // mahyor a menor.

    if(!backedges[u].empty()){
        int maxDep = -1;
        int v = -1;
        for(int i = 0 ; i < backedges[u].size() ; i ++){
            if(backedges[u][i].ff > maxDep){
                maxDep = backedges[u][i].ff;
                v = backedges[u][i].ss;
            }
        }
        int d = maxDep;
        if(d > deepest && abs(d - deep[u]) >= 3){
            for(int i = (int)stk.size() - 1 ; stk[i] != v ; i --){
                ans.pb(stk[i]);
            }
            ans.pb(v);
            return true;
        }
        deepest = max(deepest, d);
    }
    for(auto v : adj[u]){
        if(parent == v)continue;
        if(vis[v] == visited)continue;
        if(vis[v] == past)continue;
        if(respond(v, u, deepest))return true;
    }
    stk.pop_back();
    vis[u] = past;
    return false;
}
int main(){
    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(NULL);
    cin >> n >> r;
    for(int i = 0 ; i < r ; i ++){
        int u, v;
        cin >> u >> v;
        adj[u].pb(v);
        adj[v].pb(u);
    }
    for(int i = 1 ; i <= n ; i ++)vis[i] = unvisited;

    dfs(1, -1, 0);
    for(int i = 1 ; i <= n ; i ++)vis[i] = unvisited;
    if(!respond(1, -1, -10))cout << "no";
    else{
        for(auto i : ans)cout << i << " ";

    }





}

Compilation message (stderr)

indcyc.cpp: In function 'bool respond(int, int, int)':
indcyc.cpp:44:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |         for(int i = 0 ; i < backedges[u].size() ; i ++){
      |                         ~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 0 / 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