Kruskal模板

Kruskal模板

struct Edge
{
    int from,to,v;
}edge[maxn*10];
int fa[maxn];
int n,m;

int find(int x)
{
    return fa[x] == x ? x : fa[x] = find(fa[x]);
}

bool cmp(Edge a, Edge b)
{
    return a.v <b.v;
}

ll kruskal()
{
    for(int i = 1; i <= n; i++) fa[i] = i;
    sort(edge+1,edge+m+1,cmp);
    ll ans = 0;
    int cnt = 0;
    for(int i = 1; i <= m; i++){
        int x = find(edge[i].from);
        int y = find(edge[i].to);
        if(x != y){
            fa[x] = y;
            ans += (ll)edge[i].v;
            if(++cnt == n-1) break;
        }
    }
    return ans;
}