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Cod sursa(job #806767)
#include <fstream>
#include <vector>
#include <queue>
#include <algorithm>
#define N 400005
#define INF 1005
using namespace std;
ifstream in ("apm.in");
ofstream out ("apm.out");
struct Muchie {
int varf;
int cost;
};
vector <Muchie> a[N];
priority_queue <pair <int, int> > heapMinim;
int n, m;
int d[N];
int marcat[N];
int cost = 0;
int pred[N];
Muchie makeMuchie(int x, int y)
{
Muchie muchie;
muchie.varf = x;
muchie.cost = y;
return muchie;
}
void citire()
{
in >> n >> m;
int x, y, c;
while (m--) {
in >> x >> y >> c;
a[x].push_back(makeMuchie(y, c));
a[y].push_back(makeMuchie(x, c));
}
}
int main()
{
citire();
d[1] = 0;
for (int i = 2; i <= n; i++) {
d[i] = INF;
}
heapMinim.push(make_pair(0, 1));
for (int i = 1; i <= n; i++) {
while (marcat[heapMinim.top().second]) {
heapMinim.pop();
}
int x = heapMinim.top().second;
cost += heapMinim.top().first;
heapMinim.pop();
marcat[x] = 1;
for (int i = 0; i < a[x].size(); i++) {
int distanta = a[x][i].cost;
if (distanta < d[a[x][i].varf]) {
d[a[x][i].varf] = distanta;
pred[a[x][i].varf] = x;
heapMinim.push(make_pair(-distanta, a[x][i].varf));
}
}
}
out << -cost << "\n" << n - 1 << "\n";
for (int i = 2; i <= n; i++) {
out << i << " " << pred[i] << "\n";
}
return 0;
}