Cod sursa(job #812134)
#include<fstream>
#include<algorithm>
using namespace std;
ifstream f("apm.in");
ofstream g("apm.out");
#define nmax 200010
#define mmax 400010
int n,m,t[nmax],ct,nr,i,r1,r2,j,afis[mmax];
struct muchie
{
int x,y;
int cost;
} v[mmax];
int rad(int x)
{
if(t[x]==0)
return x;
else
return rad(t[x]);
}
bool cmp(muchie a,muchie b)
{
return a.cost<b.cost;
}
void citire()
{
f>>n>>m;
for(int i=1;i<=m;i++)
f>>v[i].x>>v[i].y>>v[i].cost;
}
int main()
{
citire();
sort(v+1,v+m+1,cmp);
for(i=1;nr!=n-1;i++)
{
r1=rad(v[i].x);
r2=rad(v[i].y);
if(r1!=r2)
{
ct+=v[i].cost;
nr++;
afis[++j]=i;
t[r1]=r2;
}
}
g<<ct<<'\n'<<n-1<<'\n';
for(i=1;i<=j;i++)
{
g<<v[afis[i]].x<<' '<<v[afis[i]].y<<'\n';
}
return 0;
}