Submission #1156217

#	Time	Username	Problem	Language	Result	Execution time	Memory
1156217		The_Samurai	Love Polygon (BOI18_polygon)	C++17	100 / 100	204 ms	24100 KiB

polygon

// I stand with PALESTINE



//#pragma GCC optimize("Ofast")
//#pragma GCC optimize ("unroll-loops")
//#pragma GCC target("avx,avx2")

#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
//using namespace __gnu_pbds;

#define int long long
#define ff first
#define ss second
#define sz(a) (int) (a).size()
//template<class T, class C = null_type> using ordered_tree = tree<T, C, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long double ld;

namespace io {

    template<typename F, typename S>
    ostream &operator<<(ostream &os, const pair<F, S> &p) { return os << p.ff << " " << p.ss; }

    template<typename F, typename S>
    ostream &operator<<(ostream &os, const map<F, S> &mp) {
        for (auto it: mp) { os << it << endl; }
        return os;
    }

    template<typename F>
    ostream &operator<<(ostream &os, const vector<F> &v) {
        bool space = false;
        for (F x: v) {
            if (space) os << " ";
            space = true;
            os << x;
        }
        return os;
    }

    template<typename F>
    ostream &operator<<(ostream &os, const deque<F> &d) {
        bool space = false;
        for (F x: d) {
            if (space) os << " ";
            space = true;
            os << x;
        }
        return os;
    }

    template<typename F>
    ostream &operator<<(ostream &os, const set<F> &st) {
        bool space = false;
        for (F x: st) {
            if (space) os << " ";
            space = true;
            os << x;
        }
        return os;
    }

    template<typename F>
    ostream &operator<<(ostream &os, const multiset<F> &st) {
        bool space = false;
        for (F x: st) {
            if (space) os << " ";
            space = true;
            os << x << x;
        }
        return os;
    }

    template<typename F, typename S>
    istream &operator>>(istream &is, pair<F, S> &p) { return is >> p.ff >> p.ss; }

    template<typename F>
    istream &operator>>(istream &is, vector<F> &v) {
        for (F &x: v) { is >> x; }
        return is;
    }

    long long fastread() {
        char c;
        long long d = 1, x = 0;
        do c = getchar(); while (c == ' ' || c == '\n');
        if (c == '-') c = getchar(), d = -1;
        while (isdigit(c)) {
            x = x * 10 + c - '0';
            c = getchar();
        }
        return d * x;
    }

    static bool sep = false;

    using std::to_string;

    string to_string(bool x) {
        return (x ? "true" : "false");
    }

    string to_string(const string &s) { return "\"" + s + "\""; }

    string to_string(const char *s) { return "\"" + string(s) + "\""; }

    string to_string(const char &c) {
        string s;
        s += c;
        return "\'" + s + "\'";
    }

    template<typename Type>
    string to_string(vector<Type>);

    template<typename F, typename S>
    string to_string(pair<F, S>);

    template<typename Collection>
    string to_string(Collection);

    template<typename F, typename S>
    string to_string(pair<F, S> p) { return "{" + to_string(p.ff) + ", " + to_string(p.ss) + "}"; }

    template<typename Type>
    string to_string(vector<Type> v) {
        bool sep = false;
        string s = "[";
        for (Type x: v) {
            if (sep) s += ", ";
            sep = true;
            s += to_string(x);
        }
        s += "]";
        return s;
    }

    template<typename Collection>
    string to_string(Collection collection) {
        bool sep = false;
        string s = "{";
        for (auto x: collection) {
            if (sep) s += ", ";
            sep = true;
            s += to_string(x);
        }
        s += "}";
        return s;
    }

    void print() {
        cout << endl;
        sep = false;
    }

    template<typename F, typename... Other>
    void print(F ff, Other... other) {
        if (sep) cout << " | ";
        sep = true;
        cout << to_string(ff);
        print(other...);
    }

}
using namespace io;

namespace utils {

    template<typename F, typename S>
    inline void maxs(F &a, S b) { a = a > b ? a : b; }

    template<typename F, typename S>
    inline void mins(F &a, S b) { a = a < b ? a : b; }

    template<typename F, typename S>
    long long max(F a, S b) { return a > b ? a : b; }

    template<typename F, typename S>
    long long min(F a, S b) { return a < b ? a : b; }

    constexpr long long operator "" _E(unsigned long long n) {
        long long p = 1, a = 10;
        for (int i = 0; i < n; i++) p *= a;
        return p;
    }

    random_device rd;
    mt19937 mt(rd());

    template<typename T>
    T rand(T l, T r) {
        uniform_int_distribution<T> dist(l, r);
        return dist(mt);
    };

}
using namespace utils;


#ifdef sunnatov
#define print(...) cout << "[" << #__VA_ARGS__ << "]: "; io::print( __VA_ARGS__ );
#else
#define print( ... ) 42
#endif

const int mod = 9_E + 7;
const double EPS = 1e-7;
long long doxuya = 18_E + 10;
int INF = 9_E + 10;
const char nl = '\n';

int month[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

/*

*/

void solution(istream &cin, ostream &cout, const int &test_case) {
    int n, z = 0;
    cin >> n;

    vector<int> out(n, -1);
    map<string, int> mp;
    vector<vector<int>> in(n);
    for (int i = 0; i < n; i++) {
        string s, t;
        cin >> s >> t;
        if (!mp.count(s)) mp[s] = z++;
        if (!mp.count(t)) mp[t] = z++;
        // if (test_case == 547) {
        //     cout << mp[s] << ' ' << mp[t] << endl;
        // }
        out[mp[s]] = mp[t];
        in[mp[t]].emplace_back(mp[s]);
    }
    if (n % 2) {
        cout << -1;
        return;
    }

    vector<int> vis(n), ord;
    vector<vector<int>> cycles;
    vector<bool> in_cyc(n);
    for (int i = 0; i < n; i++) {
        if (vis[i]) continue;
        vector<int> way = {i}; vis[i] = 1;
        while (!vis[out[way.back()]]) {
            way.emplace_back(out[way.back()]);
            vis[way.back()] = 1;
        }
        if (vis[out[way.back()]] == 2) {
            for (int x: way) vis[x] = 2;
            continue;
        }

        cycles.emplace_back();
        bool add = false;
        for (int x: way) {
            vis[x] = 2;
            if (x == out[way.back()]) add = true;
            if (add) cycles.back().emplace_back(x);
            if (add) in_cyc[x] = true;
        }
    }

    // print(cycles);
    auto dfs = [&](auto &dfs, int u) -> void {
        for (int v: in[u]) {
            if (!in_cyc[v]) dfs(dfs, v);
        }
        if (!in_cyc[u]) ord.emplace_back(u);
    };
    for (auto v: cycles) for (int x: v) dfs(dfs, x);
    
    // print(ord);
    int ans = 0;
    vector<bool> changed(n);
    for (int u = 0; u < n; u++) {
        if (changed[u] or u == out[u]) continue;
        if (out[out[u]] == u) {
            changed[u] = changed[out[u]] = true;
        }
    }
    for (int u: ord) {
        if (changed[u]) continue;
        int v = out[u];
        if (changed[v] or u == v) continue;
        // print(u, v);
        out[v] = u;
        ans++;
        changed[u] = changed[v] = true;
    }
    for (auto v: cycles) {
        int s = 0;
        for (int i = 0; i < sz(v); i++) if (changed[v[i]]) s = i;
        for (int i = s; i < sz(v); i++) if (!changed[v[i]]) ord.emplace_back(v[i]);
        for (int i = 0; i < s; i++) if (!changed[v[i]]) ord.emplace_back(v[i]);
    }
    for (int u: ord) {
        if (changed[u]) continue;
        int v = out[u];
        if (changed[v] or u == v) continue;
        // print(u, v);
        out[v] = u;
        ans++;
        changed[u] = changed[v] = true;
    }
    cout << ans + count(changed.begin(), changed.end(), false);
}

int32_t main() {
    clock_t startTime = clock();
    cin.tie(0)->sync_with_stdio(false);
    srand(time(0));

    std::istream &in(std::cin);
    std::ostream &out(std::cout);

    int32_t queries = 1;

#ifdef test_cases
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    cin >> queries;
#else
    // cin >> queries;
#endif

    for (int32_t test_case = 1; test_case <= queries; test_case++) {
        print(test_case);
        solution(cin, cout, test_case);
        cout << nl;
    }

// #ifdef sunnatov
//     cout << "Time: " << (int) ((double) (clock() - startTime) / CLOCKS_PER_SEC * 1000) << " ms" << endl;
// #endif

    return EXIT_SUCCESS;
}

• Subtask 1: 21 / 21
• Subtask 2: 25 / 25
• Subtask 3: 29 / 29
• Subtask 4: 25 / 25