Submission #1272065

#	Time	Username	Problem	Language	Result	Execution time	Memory
1272065		thesen	Logičari (COCI21_logicari)	C++20	10 / 110	22 ms	5736 KiB

Main

#include <bits/stdc++.h>
#define pb push_back
#define ll long long
#define vll vector <ll>
#define vbool vector<bool>
#define pairll pair<ll,ll>
#define fi first
#define sc second
#define rever greater<ll>()
using namespace std;

void solve(){
    ll n; cin >> n;

    vector<vll> path(n+1);
    for(ll i = 0, u, v; i < n; i++){
        cin >> u >> v;
        path[u].pb(v); path[v].pb(u);
    }

    ll a = 0, b = 0;
    for(ll i = 1; i <= n; i++){
        if(path[i].size() == 1){
            if(a)b = i;
            else a = i;
        }
    }
    if(a == 0){
        if(n%4)cout << -1 << endl;
        else cout << n/2 << endl;
        return;
    }

    if(a)a = path[a][0];
    if(b)b = path[b][0];
    
    vll par(n+1);
    for(ll i : path[a])par[i] = a;
    if(b){
        for(ll i : path[b]){
            if(par[i] != 0){
                cout << -1 << endl; return;
            }par[i] = b;
        }
    }

    ll res = 0;
    if(a)res++;
    if(b)res++;
    for(ll i = 1; i <= n; i++){
        if(i == a || i == b)continue;
        bool ans = 1;
        for(ll j : path[i]){
            if(par[j] != 0 && par[j] != i){ans = false; break;}
        }
        if(ans){
            res++;
            for(ll j : path[i])par[j] = i;
        }
    }
    bool ans = true;
    for(ll i = 1; i <= n; i++){
        if(!par[i])ans = false;
    }
    if(ans){
        cout << res << endl;
    }else cout << -1 << endl;
}

int main(){
    ios::sync_with_stdio(false); cin.tie(nullptr);
    ll t=1; //cin >> t;
    for(int i = 1; i <= t; i++){
        solve();
    }
}

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