Submission #1259646

#	Time	Username	Problem	Language	Result	Execution time	Memory
1259646		SzymonKrzywda	Love Polygon (BOI18_polygon)	C++20	0 / 100	61 ms	22764 KiB

polygon

#include <iostream>
#include <set>
#include <unordered_set>
#include <vector>
#include <map>
#include <string>
#include <unordered_map>

using namespace std;
using pii = pair<int, int>;
using vi = vector<int>;



int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    string s1, s2;


    int n;
    cin >> n;

    unordered_map<string, int> mapka;
    vector<int> graf(2 * n);
    vector<vi> graf2(2 * n);

    for (int i = 0; i < n; i++) {
        cin >> s1 >> s2;
        if (mapka.find(s1) == mapka.end()) mapka[s1] = mapka.size();
        if (mapka.find(s2) == mapka.end()) mapka[s2] = mapka.size();
        graf[mapka[s1]] = mapka[s2];
        graf2[mapka[s2]].push_back(mapka[s1]);
    }

    n = mapka.size();
    if (n % 2 == 1) {
        cout << -1 << '\n';
        return 0;
    }

    vector<int> indegree(n, 0);
    vector<int> stos;
    vector<vector<int>> dp(n, vector<int>(2, 0));
    vector<int> rozmiar(n, 0);

    for (int i = 0; i < n; i++) {
        indegree[i] = graf2[i].size();
        if (indegree[i] == 0) stos.push_back(i);
    }

    while (stos.size()) {
        int v = stos.back();
        stos.pop_back();

        rozmiar[v] = 1;
        for (int s : graf2[v]) {
            rozmiar[v] += rozmiar[s];
            dp[v][0] += max(dp[s][0], dp[s][1]);
        }

        for (int s : graf2[v]) {
            dp[v][1] = max(dp[v][1], dp[v][0] - max(dp[s][1], dp[s][0]) + dp[s][0] + 1);
        }
        indegree[graf[v]] --;
        if (indegree[graf[v]] == 0) stos.push_back(graf[v]);
    }

    vector<bool> polaczony(n, 0);
    vector<int> pop_cykl(n, 0);
    int wynik = 0;

    for (int i = 0; i < n; i++) {
        if (indegree[i] == 0) continue;
        int suma_poddrzew = 0, suma_wynik = 0;
        for (int s : graf2[i]) {
            if (indegree[s] != 0) continue;

            if (dp[s][0] == dp[s][1]) {
                polaczony[i] = 1;
            }
            suma_poddrzew += rozmiar[s];
            suma_wynik += max(dp[s][0], dp[s][1]);
        }

        pop_cykl[graf[i]] = i;
        //cout << i << ' ' << suma_poddrzew << ' ' << suma_wynik << ' ' << polaczony[i] << '\n';
        wynik += suma_poddrzew - suma_wynik;

        if (i == graf[graf[i]] && graf[i] != i) {
            polaczony[i] = 1;
        }
    }
    //cout << wynik << '\n';


    for (int i = 0; i < n; i++) {
        if (indegree[i] == 0 || polaczony[i]) continue;
        //cout << "O: " << i << ' ' << graf[i] << ' ' << pop_cykl[i] << ' ' << polaczony[graf[i]] << ' ' << polaczony[pop_cykl[i]] << '\n';

        int akt_v = i, ile = 0;

        while (!polaczony[akt_v]) {
            polaczony[akt_v] = 1;
            akt_v = graf[akt_v];
            ile++;
        }

        akt_v = pop_cykl[i];
        while (!polaczony[akt_v]) {
            polaczony[akt_v] = 1;
            akt_v = pop_cykl[akt_v];
            ile++;
        }

        wynik += ile / 2 + 2 * (ile % 2);
    }


    cout << wynik << '\n';



    return 0;
}

• Subtask 1: 0 / 21
• Subtask 2: 0 / 25
• Subtask 3: 0 / 29
• Subtask 4: 0 / 25