Cod sursa(job #1268981)

Utilizator gabrielinelusGabriel-Robert Inelus gabrielinelus Data 21 noiembrie 2014 18:42:20
Problema Arbore partial de cost minim Scor 60
Compilator cpp Status done
Runda Arhiva educationala Marime 1.44 kb
#include <cstdio>
#include <vector>
#include <algorithm>
#include <cstring>

#define Nmax 200005
#define INF 0x3f3f3f3f

using namespace std;
int N,M,DP[Nmax],daddy[Nmax],used[Nmax];
vector<pair<int,int> > G[Nmax];

void Read()
{
    scanf("%d%d",&N,&M);
    int a,b,c;
    for(int i = 1; i <= M; ++i){
        scanf("%d%d%d",&a,&b,&c);
        G[a].push_back(make_pair(c,b));
        G[b].push_back(make_pair(c,a));
    }
    memset(DP,INF,sizeof(DP));
    DP[1] = 0;
}

int selectmin()
{
    int mini = INF,pzmin;
    for(int i = 1; i <= N; ++i)
        if(DP[i] < mini && !used[i]){
            mini = DP[i];
            pzmin = i;
        }
    used[pzmin] = 1;
    return pzmin;
}

void Prim(int k) /// N^2
{
    for(int step = 1; step <= N; ++step){
        k = selectmin();
        for(vector<pair<int,int> >::iterator it = G[k].begin(); it != G[k].end(); ++it){
            if(used[it->second]) continue;
            if(DP[it->second] > it->first){
                DP[it->second] = it->first;
                daddy[it->second] = k;
            }
        }
    }
}

void Print()
{
    int cst = 0;
    for(int i = 1; i <= N; ++i)
        cst += DP[i];
    printf("%d\n%d\n",cst,N-1);
    for(int i = 2; i <= N; ++i)
        printf("%d %d\n",i,daddy[i]);
}

int main()
{
    freopen("apm.in","r",stdin);
    freopen("apm.out","w",stdout);

    Read();
    Prim(1);
    Print();

    return 0;
}