Cod sursa(job #1238918)

Utilizator diana97Diana Ghinea diana97 Data 7 octombrie 2014 22:18:13
Problema Arbore partial de cost minim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.66 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;

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

const int nmax = 200000;

int n, m;
int cost, nrmuchii;
struct Muchie {
    int a, b, cost;
    bool kept;
    Muchie (int a, int b, int cost) {
        this->a = a;
        this->b = b;
        this->cost = cost;
        this-> kept = false;
    };
};

int v[nmax + 1];
int t[nmax + 1], r[nmax + 1];
vector <Muchie> muchii;

void citeste () {
    f >> n >> m;
    int a, b, c;
    for (int i = 1; i <= m; i++) {
        f >> a >> b >> c;
        muchii.push_back (Muchie (a, b, c));
    }
}

bool conditie (Muchie a, Muchie b) {
    return a.cost < b.cost;
}

int cauta (int x) {
    int rd = x, y;
    while (rd != t[rd]) rd = t[rd];
    return rd;
}

void uneste (int x, int y) {
    if (r[x] > r[y]) t[y] = x;
    else t[x] = y;
    if (r[x] == r[y]) r[y]++;
}

void APM () {
    int ra, rb;
    for (int i = 0; i < m; i++) t[i] = i, r[i] = 1;
    for (int i = 0; i < m; i++) {
        ra = cauta(muchii[i].a);
        rb = cauta(muchii[i].b);
        if (ra != rb) {
            nrmuchii++;
            cost += muchii[i].cost;
            muchii[i].kept = true;
            uneste(ra, rb);
            //for (int i = 1; i <= n; i++) cout << v[i] << ' ';
            //cout << endl;
        }
    }
}

void scrie () {
    g << cost << '\n' << nrmuchii << '\n';
    for (int i = 0; i < m; i++)
        if (muchii[i].kept) g << muchii[i].b << ' ' << muchii[i].a << '\n';
}

int main () {
    citeste ();

    for (int i = 1; i <= n; i++) v[i] = i;
    sort (muchii.begin (), muchii.end (), conditie);

    APM ();

    scrie ();

    return 0;
}