Cod sursa(job #2673952)

Utilizator iancupoppPopp Iancu Alexandru iancupopp Data 18 noiembrie 2020 11:52:04
Problema Arbore partial de cost minim Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.51 kb
#include <fstream>
#include <vector>
#include <set>

using namespace std;

struct muchie {
    int nod;
    int cost;
    bool operator <(const muchie& alt) const{
        return this->cost < alt.cost;
    }
};

const int N = 2e5, INF = 1 << 30;

vector<muchie> gr[N];
multiset<muchie> s;
int cmin[N], cor[N];
bool exista[N];
pair<int, int> rez[N];

void cost_minim(int nod) {
    for (auto i : gr[nod])
        if (!exista[i.nod] && i.cost < cmin[i.nod]) {
            cmin[i.nod] = i.cost;
            cor[i.nod] = nod;
            s.insert(i);
        }
}

int main() {
    ifstream in("apm.in");
    ofstream out("apm.out");
    
    int n, m, x, y, c;
    in >> n >> m;
    while (m--) {
        in >> x >> y >> c;
        --x, --y;
        gr[x].push_back({ y, c });
        gr[y].push_back({ x, c });
    }
    for (int i = 0; i < N; ++i)
        cmin[i] = INF;
    cost_minim(0);
    exista[0] = true;
    int nod, cost, ctot = 0;
    for (int i = 1; i < n; ++i) {
        nod = s.begin()->nod;
        while (exista[nod]) {
            s.erase(s.begin());
            nod = s.begin()->nod;
        }
        s.erase(s.begin());
        exista[nod] = true;
        cost = cmin[nod];
        ctot += cost;
        rez[i - 1] = { nod, cor[nod] };
        cost_minim(nod);
    }
    out << ctot << '\n' << n - 1 << '\n';
    for (int i = 0; i < n - 1; ++i)
        out << rez[i].first + 1 << ' ' << rez[i].second + 1 << '\n';

    in.close();
    out.close();
    return 0;
}