Submission #582689

#	Time	Username	Problem	Language	Result	Execution time	Memory
582689		dxz05	Logičari (COCI21_logicari)	C++14	10 / 110	102 ms	83660 KiB

Main

#pragma GCC optimize("Ofast,O2,O3,unroll-loops")
#pragma GCC target("avx2")

#include <bits/stdc++.h>

#include <random>

using namespace std;

void debug_out() { cerr << endl; }

template<typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << "[" << H << "]";
    debug_out(T...);
}

#ifdef dddxxz
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

#define SZ(s) ((int)s.size())
#define all(x) (x).begin(), (x).end()
#define lla(x) (x).rbegin(), (x).rend()
#define bpc(x) __builtin_popcount(x)
#define bpcll(x) __builtin_popcountll(x)

clock_t startTime;

double getCurrentTime() {
    return (double) (clock() - startTime) / CLOCKS_PER_SEC;
}

#define MP make_pair

typedef long long ll;
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
const double eps = 0.000001;
const int MOD = 1e9 + 7;
const int INF = 1000000101;
const long long LLINF = 1223372000000000555;
const int N = 1e6 + 3e2;
const int M = 1111;

vector<int> g[N];

set<int> groups[N];

int color[N];

void solve(int TC) {
    int n;
    cin >> n;

    fill(color + 1, color + n + 1, -1);

    for (int i = 1; i <= n; i++){
        int x, y;
        cin >> x >> y;
        g[x].push_back(y);
        g[y].push_back(x);
    }

    for (int i = 1; i <= n; i++){
        for (int j : g[i]) groups[i].insert(j);
    }

    bool ok = false;
    for (int i = 1; i <= n; i++){
        if (g[i].size() == 1){
            color[g[i][0]] = 1;
            ok = true;
        }
    }

    if (!ok){
        cout << (n % 4 == 0 ? n / 2 : -1);
        return;
    }

    for (int it = 1; it <= (n + 5) * (n + 5); it++){
        for (int i = 1; i <= n; i++){
            int black = 0, white = 0;
            for (int j : groups[i]){
                if (color[j] == 0) white++;
                if (color[j] == 1) black++;
            }

            int sz = (int)groups[i].size();

            if (black == 1){
                for (int j : groups[i]){
                    if (color[j] == -1) color[j] = 0;
                }
            } else if (white == sz - 1){
                for (int j : groups[i]){
                    if (color[j] == -1) color[j] = 1;
                }
            }

        }

    }

//    for (int i = 1; i <= n; i++) cout << color[i] << ' '; cout << endl;

    int ans = 0;
    for (int i = 1; i <= n; i++){
        assert(color[i] != -1);

        ans += color[i];

        int cnt = 0;
        for (int j : g[i]) cnt += color[j] == 1;

        if (cnt != 1){
            cout << -1;
            return;
        }
    }

    cout << ans << endl;

}

int main() {
    startTime = clock();
    ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);

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

    int TC = 1;
//    cin >> TC;

    for (int test = 1; test <= TC; test++) {
        //debug(test);
        //cout << "Case #" << test << ": ";
        solve(test);
    }

#ifdef dddxxz
    cerr << endl << "Time: " << int(getCurrentTime() * 1000) << " ms" << endl;
#endif

    return 0;
}

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