Kruskal WA 八个 求找错

#include<cstdio>
#include<algorithm>
using namespace std;
const int maxn = 5000 + 10 ;
const int maxm = 200000 + 10 ;
int father[maxn];
struct point{
    int l;
    int r;
    int w;
}a[maxm];
int cmp(point a,point b)
{
    return a.w<b.w;
}
int find(int x)
{
    if(father[x]!=x) father[x]=find(father[x]);
    return father[x];
}
void unionn(int r1,int r2)
{
    if(find(r1)!=find(r2))
    father[r2]=r1;
}
int main()
{
    int n,m,ans=0,rp=0;
    scanf("%d%d",&n,&m);
    for(int i=1;i<=m;i++)
    scanf("%d%d%d",&a[i].l,&a[i].r,&a[i].w);
    sort(a+1,a+m+1,cmp);
    for(int i=1;i<=n;i++)
    father[i]=i;
    for(int i=1;i<=m;i++)
    {
        if(find(a[i].l)!=find(a[i].r))
        {
            unionn(a[i].l,a[i].r);
            ans+=a[i].w;
            rp++;
        }
        if(rp==n-1)
        break;
    }
    printf("%d",ans);
    return 0;
}