kruskal求最小生成树

#include <iostream>
#include <algorithm>
using namespace std;
const int N = 100010;
int p[N];
struct Edge{
    int a, b, w;
    bool operator < (const Edge &W) const
    {
        return w < W.w;
    }
}edges[N];
int find(int x)
{
    if(x != p[x]) p[x] = find(p[x]);
    return p[x];
}
int main()
{
    int n, m;
    cin>>n>>m;
    for(int i = 0; i < m; i++)
    {
        int a, b, w;
        cin>>a>>b>>w;
        edges[i] = {a, b, w};
    }
    sort(edges,edges + m);
    for(int i = 1; i <= n; i++) p[i] = i;
    int res = 0, cnt = 0;
    for(int i = 0;i<m;i++)
    {
        int a = edges[i].a, b = edges[i].b, w = edges[i].w;
        a = find(a), b = find(b);
        if(a != b)
        {
            p[a] = b; //两个不连通的点进行合并
            res += w;  //最小生成树边权之和，边数+1
            cnt++;
        }
    }
    if(cnt < n - 1) cout<<"impossible"<<endl;
    else cout<<res<<endl;
}