Cod sursa(job #1002421)

Utilizator cat_red20Vasile Ioana cat_red20 Data 27 septembrie 2013 18:31:42
Problema Arbore partial de cost minim Scor 90
Compilator cpp Status done
Runda Arhiva educationala Marime 1.62 kb
#include<fstream>
#include<set>
#include<vector>
#define INF 1<<30
using namespace std;
int m,n,tata[200001],dist[200001],s,viz[200001];
vector<pair<int,int> > v[200001];
set<pair<int,int> > cost;
ifstream fin("apm.in");
ofstream fout("apm.out");

void Citire()
{
    int x,y,c;
    fin>>n>>m;
    for(int i=1;i<=m;i++)
    {
        fin>>x>>y>>c;
        v[x].push_back(make_pair(y,c));
        v[y].push_back(make_pair(x,c));
    }
}

void Initializare()
{
    for(int i=2;i<=n;i++)
    {
        dist[i]=INF;
    }
    for(int i=0;i<v[1].size();i++)
    {
        cost.insert(make_pair(v[1][i].second,v[1][i].first));
        tata[v[1][i].first]=1;
        dist[v[1][i].first]=v[1][i].second;
    }
    viz[1]=1;
}

void Prim()
{
    int nod;
    for(int i=1;i<n;i++)
    {

        nod=(*cost.begin()).second;
        while(viz[nod]==1)
        {
            cost.erase(*cost.begin());
            nod=(*cost.begin()).second;
        }
        viz[nod]=1;
        s+=dist[nod];
        cost.erase(*cost.begin());
        for(int j=0;j<v[nod].size();j++)
        {
            if(dist[v[nod][j].first]>v[nod][j].second && viz[v[nod][j].first]==0)
            {
                dist[v[nod][j].first]=v[nod][j].second;
                cost.insert(make_pair(v[nod][j].second,v[nod][j].first));
                tata[v[nod][j].first]=nod;
            }
        }
    }
}

void Afisare()
{
    fout<<s<<"\n"<<n-1<<"\n";
    for(int i=2;i<=n;i++)
        fout<<i<<" "<<tata[i]<<"\n";


}

int main()
{
    Citire();
    Initializare();
    Prim();
    Afisare();
    return 0;
}