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kruskal vector.cpp
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kruskal vector.cpp
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#include <cstdio>
#include <vector>
#include <algorithm>
using namespace std;
#define pb(x) push_back(x)
#define MAXN 1001
typedef pair<int,int> pii;
// ( w (u, v) ) format
vector< pair< int, pii > > g, mst;
int parent[MAXN];
int findset(int x)
{
if(x != parent[x])
parent[x] = findset(parent[x]);
return parent[x];
}
int kruskal(int e)
{
int i, pu, pv,total;
sort(g.begin(), g.end()); // increasing weight
for(i=total=0; i<e; i++)
{
pu = findset(g[i].second.first);
pv = findset(g[i].second.second);
if(pu != pv)
{
mst.pb(g[i]); // add to tree
total += g[i].first; // add edge cost
parent[pu] = parent[pv]; // link
}
}
return total;
}
void reset(int n)
{
g.clear();
mst.clear();
for(int i=0; i<n; i++) parent[i] = i;
}
int main()
{
int i, u, v, w ,n, e;
scanf("%d %d", &n, &e);
reset(n);
for(i=0; i<e; i++)
{
scanf("%d %d %d", &u, &v, &w);
g.push_back(pair< int, pii >(w, pii(u, v)));
}
printf("%d",kruskal(e)); // runs kruskal and construct mst vector
return 0;
}