Kruskal

zhuyuhao1123 · 2025-10-21 15:53:55 · 算法·理论

原题：P3366 【模板】最小生成树

#include<bits/stdc++.h>
#define M 2147483647
using namespace std;
struct node
{
    int u,v,w;
}a[200001];
int f[5001],n,m,ans,sum;
bool b[5001];
inline int findfather(int x)
{
    if(f[x]==x) return x;
    return f[x]=findfather(f[x]);
}
inline bool cmp(node x,node y)
{
    return x.w<y.w;
}
void kruskal()
{
    sort(a+1,a+m+1,cmp);
    for(register int i=1;i<=m;++i)
    {
        int fu=findfather(a[i].u),fv=findfather(a[i].v);
        if(fu==fv) continue;
        ans+=a[i].w,f[fu]=fv;
        if(++sum==n-1) break;
    }
}
int main()
{
    cin>>n>>m;
    for(register int i=1;i<=n;++i) f[i]=i;
    for(register int i=1;i<=m;++i)
    cin>>a[i].u>>a[i].v>>a[i].w;
    kruskal();
    if(sum==n-1) cout<<ans;
    else cout<<"None";
    return 0;
}