Cod sursa(job #2663614)

Utilizator BAlexandruBorgovan Alexandru BAlexandru Data 26 octombrie 2020 21:36:34
Problema Arbore partial de cost minim Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.76 kb
#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;

ifstream f("apm.in");
ofstream g("apm.out");

struct edge
{
    int node1, node2;
    int cost;
};

bool cmp(edge a, edge b)
{
    return a.cost < b.cost;
}

int n, m;

vector < edge > e;
vector < int > sol;
vector < int > parent, h;

void uneste(int x, int y)
{
    while (parent[x])
        x = parent[x];

    while (parent[y])
        y = parent[y];

    if (x == y)
        return;

    if (h[x] <= h[y])
    {
        parent[x] = y;
        h[y] = max(h[y], h[x] + 1);
    }
    else
    {
        parent[y] = x;
        h[x] = max(h[x], h[y] + 1);
    }
}


bool verif(int x, int y)
{
    int m1 = x, m2 = y;

    while (parent[m1])
        m1 = parent[m1];

    while (parent[m2])
        m2 = parent[m2];

    int aux;

    while (parent[x])
    {
        aux = x;
        x = parent[x];
        parent[aux] = m1;
    }

    while (parent[y])
    {
        aux = y;
        y = parent[y];
        parent[aux] = m2;
    }

    return m1 != m2;
}

int main()
{
    f >> n >> m;

    e.resize(m);
    h.resize(n + 1);
    parent.resize(n + 1);

    for (int i=0; i<m; i++)
        f >> e[i].node1 >> e[i].node2 >> e[i].cost;

    sort(e.begin(), e.end(), cmp);

    int costTotal = 0;
    for (int i=0; i<m; i++)
        if (verif(e[i].node1, e[i].node2))
        {
            uneste(e[i].node1, e[i].node2);
            costTotal += e[i].cost;

            sol.push_back(i);
            if (sol.size() == n - 1)
                break;
        }

    g << costTotal << "\n";
    g << sol.size() << "\n";
    for (auto it : sol)
        g << e[it].node1 << " " << e[it].node2 << "\n";

    return 0;
}