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Cod sursa(job #805691)
#include<stdio.h>
#include<vector>
#include<set>
#include<utility>
#define inf 2000
#define nmax 200005
using namespace std;
struct vecin{long n, c;};
long a, b, c, n, m, poz, rez, i;
vector <vecin> ma[nmax];
vector <vecin> ::iterator it;
set < pair < long, long> > h;
pair < long, long > mchal;
vecin el, mch, cmin[nmax];
bool fol[nmax];
void citire()
{
scanf("%ld %ld",&n,&m);
for(i=1;i<=m;i++)
{
scanf("%ld %ld %ld",&a,&b,&c);
el.n=b; el.c=c; ma[a].push_back(el);
el.n=a; el.c=c; ma[b].push_back(el);
}
}
void rezolvare()
{
fol[1]=1; poz=1;
for (i=1;i<=n-1;i++)
{
for (it=ma[poz].begin();it!=ma[poz].end();it++)
{
mch=(*it);
if (!fol[mch.n])
if (cmin[mch.n].c>mch.c)
{
if(cmin[mch.n].c!=inf)
h.erase(make_pair(cmin[mch.n].c,mch.n));
cmin[mch.n].c=mch.c; cmin[mch.n].n=poz;
h.insert(make_pair(mch.c,mch.n));
}
}
while ( (fol[(*h.begin()).second]) && (fol[cmin[(*h.begin()).second].n]) )
h.erase(h.begin());
mchal=*h.begin();
if(fol[mchal.second])
{ poz=cmin[mchal.second].n; fol[cmin[mchal.second].n]=1; }
else
{ poz=mchal.second; fol[mchal.second]=1; }
h.erase(h.begin());
rez+=mchal.first;
}
}
void afisare()
{
printf("%ld\n",rez);
printf("%ld\n",n-1);
for (i=2;i<=n;i++)
printf("%ld %ld\n",cmin[i].n, i);
}
int main()
{
freopen("apm.in","r",stdin);
freopen("apm.out","w",stdout);
citire();
for (i=1;i<=n;i++)
cmin[i].c=inf;
rezolvare();
afisare();
return 0;
}