OIcode/kruskal.cpp at main · innova-1/OIcode · GitHub

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#include<bits/stdc++.h>
using namespace std;
#define int long long
#define N 5000
#define M 200005
int n,m;
int head[N],to[M],val[M],nex[M],cnt,ans;
void add(int u,int v,int w)
{
	to[++cnt]=v;
	val[cnt]=w;
	nex[cnt]=head[u];
	head[u]=cnt;
	return;
}
struct E{
	int u;int v;int w;
}edge[M];
bool cmp(E x,E y)
{
	return x.w<y.w;
}
int f[N];
int find(int x)
{
	if(f[x]==x)return x;
	return f[x]=find(f[x]);
}
void merge(int x,int y)
{
	x=find(f[x]);
	y=find(f[y]);
	f[x]=y;
	return;
}
bool ck(int x,int y)
{
	return find(x)==find(y);
}
void init()
{
	for(int i=1;i<=m;i++)
	{
		cin>>edge[i].u>>edge[i].v>>edge[i].w;
	}
	sort(edge+1,edge+m+1,cmp);
	for(int i=1;i<=n;i++)f[i]=i;
	for(int i=1;i<=m;i++)
	{
		if(ck(edge[i].u,edge[i].v))continue;
		add(edge[i].u,edge[i].v,edge[i].w);
		merge(edge[i].u,edge[i].v);
		ans+=edge[i].w;
	}
}
signed main()
{
	cin>>n>>m;
	init();
	cout<<ans<<endl;
	return 0;
}