Cod sursa(job #2870574)

Utilizator VipioanaMirea Oana Teodora Vipioana Data 12 martie 2022 14:02:30
Problema Arbore partial de cost minim Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.13 kb
#include <fstream>
#include <vector>
#include <queue>
#define inf 1000000001
using namespace std;
ifstream cin("apm.in");
ofstream cout("apm.out");
const int N=2e5+1;
int n,m,d[N],pred[N],cost;
vector <pair<int,int>> a[N];
priority_queue <pair<int,int>> q;
bool selectat[N];

int prim(){
    for(int i=1; i<=n; i++)
        d[i]=inf;
    d[1]=0;
    q.push({0,1});
    while(!q.empty()){
        int x=q.top().second;
        q.pop();
        if(selectat[x])
            continue;
        selectat[x]=1;
        cost+=d[x];
        for(auto j:a[x]){
            int y=j.first;
            int c=j.second;
            //if(selectat[y])
                //continue;
            if(c<d[y]){
                d[y]=c;
                pred[y]=x;
                q.push({-c,y});
            }
        }
    }
    return cost;
}

int main()
{
    cin>>n>>m;
    for(int i=1; i<=m; i++){
        int x,y,c;
        cin>>x>>y>>c;
        a[x].push_back({y,c});
        a[y].push_back({x,c});
    }
    cout<<prim()<<'\n'<<n-1<<'\n';
    for(int i=2; i<=n; i++)
        cout<<i<<" "<<pred[i]<<'\n';
    return 0;
}