Submission #491397

#	Time	Username	Problem	Language	Result	Execution time	Memory
491397		julian33	Logičari (COCI21_logicari)	C++14	10 / 110	62 ms	15080 KiB

Main

#include <bits/stdc++.h>

using namespace std;

#ifdef LOCAL
#define deb(...) logger(#__VA_ARGS__, __VA_ARGS__)
template<typename ...Args>
void logger(string vars, Args&&... values) {
    cerr<<vars<<" = ";
    string delim="";
    (...,(cerr<<delim<<values,delim=", "));
    cerr<<"\n";
}
#else
#define deb(...) logger(#__VA_ARGS__, __VA_ARGS__)
template<typename ...Args>
void logger(string vars, Args&&... values) {}
#endif

#define pb push_back
#define sz(x) (int)(x.size())
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
template<typename T> inline void maxa(T& a,T b){a=max(a,b);}
template<typename T> inline void mina(T& a,T b){a=min(a,b);} 
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int mxN=2e5+5; //make sure this is right
const int mod=1e9+7;

vector<int> graph[mxN];
int done[mxN],blue[mxN],never[mxN],deg[mxN];
void dfs(int at){
    int t=0;
    for(int &i:graph[at]){
        if(blue[i]) t=1;
    }
    for(int &i:graph[at]){
        if(never[i] || blue[i]) continue;
        if(t){
            never[i]=1;
            dfs(i);
        } else{
            blue[i]=1;
            dfs(i);
        }
    }
}

int main(){
    cin.sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    #ifdef LOCAL
        freopen("input.txt","r",stdin);
        freopen("output.txt","w",stdout);
    #endif

    int n; cin>>n;
    for(int i=0;i<n;i++){
        int a,b; cin>>a>>b;
        graph[a].pb(b);
        graph[b].pb(a);
        deg[a]++;
        deg[b]++;
    }
    queue<int> q;
    for(int i=1;i<=n;i++){
        if(deg[i]==1) q.push(i);
    }
    if(!sz(q)){
        if(n%4){
            cout<<-1<<"\n";
        } else{
            int ans=0;
            blue[1]=1;
            blue[graph[1][0]]=1;
            dfs(graph[1][0]);
            for(int i=1;i<=n;i++)
                ans+=blue[i];
            cout<<ans<<"\n";
        }
        return 0;
    }
    int ans=0;
    while(!q.empty()){
        int at=q.front();
        q.pop();
        done[at]=1;
        ans++;
        for(int &i:graph[at]){
            if(never[i]) continue;
            blue[i]=1;
            for(int &j:graph[i]){
                if(!done[j]){
                    done[j]=1;
                    for(int &k:graph[j]){
                        if(blue[k]) continue;
                        if(!never[k]){
                            for(int &u:graph[k]){
                                if(blue[u] || done[u]) continue;
                                deg[u]--;
                                if(!deg[u]){
                                    cout<<-1<<"\n";
                                    return 0;
                                }
                                if(deg[u]==1) q.push(u);
                            }
                        }
                        never[k]=1;
                    }
                }
            }
        }
    }
    cout<<ans<<"\n";
}

• Subtask 1: 10 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 40
• Subtask 4: 0 / 50