Probably doesn't work

pair<int,int> deg[500]; // {degree, index}

void run(){
    int n; cin>>n;
    for (int i=0; i<=n; i++) cin>>deg[i].first, deg[i].second=i+1;
    sort(deg,deg+n);

    vector<int> res;

    for (int i=0; i<=n; i++){
        ll sum=0;
        ll capsum=0;

        // copy in degrees in decreasing order
        vector<int> all;
        for (int j=n; j>=0; --j) if (i!=j) all.push_back(deg[j].first), sum+=deg[j].first;

        // check that degree sum is even
        if (sum%2!=0) continue;

        bool ok=true;
        ll capgt=-1; // number of items greater than the cap
        for (int k=n; k>=1; k--){
            // update sums of deg[1..k]
            if (k<n){
                sum-=all[k];
            }

            // update sums of min(deg[k+1..n],k)
            if (k<n){
                if (all[k]>k) capgt=max(capgt, (ll)(k+1));
                if (capgt!=-1){
                    while (capgt<n and all[capgt]>k) ++capgt;
                    capsum-=(capgt-k);
                }
                capsum+=min(all[k],k+1);
            }

            // check erdos-gallai theorem holds
            ok &= (sum <= k*(k-1) + capsum);
        }

        if (ok) res.push_back(deg[i].second);
    }

    sort(res.begin(),res.end());
    cout<<res.size()<<endl;
    for (int i=0; i<res.size(); i++) cout<<res[i]<<endl;
}