Cod sursa(job #2650693)

Utilizator KPP17Popescu Paul KPP17 Data 19 septembrie 2020 18:46:00
Problema Arbore partial de cost minim Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.72 kb

/// Aceasta sursa face sortarea si se ocupa de multimile disjuncte manual


#define fisier "apm"


#ifdef fisier
    #include <fstream>
    std::ifstream in(fisier ".in");
    std::ofstream out(fisier ".out");
#else
    #include <iostream>
    #define in std::cin
    #define out std::cout
#endif



const int
N = 100000,
M = 400000,
COST_MIN = -1000, COST_MAX = 1000;

int n, m;

#include <utility>
struct Muchie
{
    std::pair<int, int> incidente;
    int cost;

    inline bool operator <= (Muchie& alta)
    {return cost <= alta.cost;}
}
*muchii;



void sorteaza(int start, int end)
{
    if (start == end)
        return;

    int piv = start;
    for (int itr = start; itr < end; itr++)
        if (muchii[itr] <= muchii[end - 1])
            std::swap(muchii[piv++], muchii[itr]);

    sorteaza(start, piv - 1);
    sorteaza(piv, end);
}



#include <vector>
namespace arbore_partial
{
    int
    *set,
    nr_muchii,
    cost;

    Muchie* muchii;

    int radacina(int rad)
    {
        std::vector<int> drum;
        while (set[rad])
        {
            drum.push_back(rad);
            rad = set[rad] - 1;
        }
        for (int varf: drum)
            set[varf] = rad + 1;
        return rad;
    }

    void gestioneaza(Muchie& muchie)
    {
        int
        &a = muchie.incidente.first,
        &b = muchie.incidente.second,
        rad_a = radacina(a),
        rad_b = radacina(b);

        if (rad_a != rad_b) // nu sunt in aceeasi componenta conexa (in arborele partial)
        {
            set[rad_a] = rad_b + 1;
            muchii[nr_muchii++] = muchie;
            cost += muchie.cost;
        }
    }
}

using arbore_partial::gestioneaza;
using arbore_partial::radacina;



int main()
{
    std::ios_base::sync_with_stdio(false);
    #ifndef fisier
        std::cin.tie(NULL);
    #endif

    in >> n >> m;
    muchii = new Muchie[m];

    for (int i = 0; i < m; i++)
    {
        int a, b, cost;
        in >> a >> b >> cost;
        a--, b--;
        muchii[i] = {{a, b}, cost};
    }

    sorteaza(0, m);
    arbore_partial::set = new int[n]();
    arbore_partial::muchii = new Muchie[n - 1];

    for (int i = 0; i < m; i++)
        gestioneaza(muchii[i]);

    delete[] muchii;
    delete[] arbore_partial::set;

    out
    << arbore_partial::cost << '\n'
    << n - 1 << '\n';

    for (int i = 0; i < n - 1; i++)
    {
        auto& incidente = arbore_partial::muchii[i].incidente;

        int
        &a = incidente.first,
        &b = incidente.second;

        out << a + 1 << ' ' << b + 1 << '\n';
    }

    delete[] arbore_partial::muchii;
}