40分求助？

评测链接

#include <bits/stdc++.h>
#define ll long long
using namespace std;

ll n,m,k,f[400005],s[400005],build[400005],sum[400005],ans[400005];
vector<ll> g[400005];

ll find(ll kk)
{
    if (f[kk]!=kk)
        f[kk]=find(f[kk]);
    return f[kk];
}

int main()
{
    cin>>n>>m;
    for (ll i=0;i<n;i++)
    {
        f[i]=i;
        sum[i]=1;
    }
    for (ll i=0;i<m;i++)
    {
        ll a,b;
        cin>>a>>b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    cin>>k;
    for (ll i=0;i<k;i++)
    {
        cin>>s[i];
        build[s[i]]=1;
    }
    ll cnt=n-k;
    for (ll i=0;i<n;i++)
        if (build[i]==0)
            for (ll j=0;j<g[i].size();j++)
                if (build[g[i][j]]==0&&find(g[i][j])!=find(i))
                {
                    f[find(g[i][j])]=find(j);
                    cnt--;
                }
    ans[k]=cnt;
    for (ll i=k-1;i>=0;i--)
    {
        build[s[i]]=0;
        cnt++;
        for (ll j=0;j<g[s[i]].size();j++)
            if (build[g[s[i]][j]]==0&&find(g[s[i]][j])!=find(s[i]))
            {
                f[find(g[s[i]][j])]=find(s[i]);
                cnt--;
            }
        ans[i]=cnt;
    }
    for (ll i=0;i<=k;i++)
        cout<<ans[i]<<endl;
    return 0;
}