PrimeFactorization using Sieve

//In the Name of Allah Most Gracious, Most Merciful//
/*If you want something you've never had, you have  to do something you never did.*/

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


#define pb push_back
#define ll long long
#define pii pair<ll,ll>
#define pll pair<ll,ll>
#define M 10000007
#define INF 1e9
#define INFL 1e18
#define PI acos(-1)
#define mp make_pair
#define fast_in_out ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
//const ll fx[]= {+1,-1,+0,+0};
//const ll fy[]= {+0,+0,+1,-1};
//const ll fx[]={+0,+0,+1,-1,-1,+1,-1,+1};   // Kings Move
//const ll fy[]={-1,+1,+0,+0,+1,+1,-1,-1};  // Kings Move
//const ll fx[]={-2, -2, -1, -1,  1,  1,  2,  2};  // Knights Move
//const ll fy[]={-1,  1, -2,  2, -2,  2, -1,  1}; // Knights Move
ll SPF[M+10];
bool mark[M+10];

void sieve_SPF()
{
    for(ll i=2;i<=M;i+=2)
    {
        SPF[i]=2;

    }

    for(ll i=3;i<M;i+=2)
    {
        if(mark[i]==false)
        {
            SPF[i]=i;
            for(ll j=i;(j*i)<M;j+=2)
            {

                if(mark[i*j]==false)
                {
                    mark[i*j]=true;
                    SPF[i*j]=i;
                }
            }
        }
    }
}

vector<int> get_prime_div(int x)
{
    vector<int>ret;
    while(x!=1)
    {
        ret.pb(SPF[x]);
        x=x/SPF[x];

    }
    return ret;
}
int main()
{
    fast_in_out;
   //  #ifndef ONLINE_JUDGE
   //    freopen("input.txt","r",stdin);
   //    freopen("output.txt","w",stdout);
  //   #endif
  //cout<<"AS"<<endl;
  sieve_SPF();
 // cout<<"asd"<<endl;
  for(ll i=2;i<=100;i++)
  {
      vector<int>v;
      v=get_prime_div(i);
      cout<<"NUM "<<i<<": ";
      for(int i=0;i<v.size();i++)
      {
          cout<<v[i]<<" ";
      }
      cout<<endl;
  }

}