Dijkestra nth distance

void dijkestrea(int n){
    priority_queue <pii, vector <pii>,  greater <pii> > q;
    q.push({0, 1});
    while(!q.empty()){
        int a = q.top().first;
        int b = q.top().second;
        q.pop();
        if(ara[b].size()==0) ara[b].push_back(a);
        else if(ara[b].back()!=a) ara[b].push_back(a);
        if(ara[b].size()>2) continue;
        for(int i=0;i<g[b].size();i++){
            if(ara[g[b][i]].size()==2) continue;
            q.push({a+d[b][i], g[b][i]});
        }
    }
}