Whats wrong with anything here?
#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using ui=unsigned int;
int main() {
    //ios::sync_with_stdio(0);
    //cin.tie(0);
    ll n;cin>>n;
    if(!n){
        cout<<10;
        return 0;
    }
    else if(n<10){
        cout<<n;
        return 0;
    }
    vector<int>v;
    ll l=n;
    for(bool q=1;q;){
        q=0;
        for(ll i=9;i>1;i--){
            if(l%i==0){
                l/=i;
                v.push_back(i);
                q=1;

            }
        }
    }
    v.push_back(l);
    sort(v.begin(),v.end());
    if(v[0]==1)for(int i=1;i<v.size();i++)cout<<v[i];
    else cout<<-1;
    return 0;
}

Ok later I figured out that instead of dividing by all the numbers consecutively, dividing by the current factor between 2 to 9 repeatedly until it isn't a factor provides the fewest digits. For example, input 1000000 gives 245555558 in the above program, whereas 2 and 4 could be replaced by 8 for better result.

Edited by author 14.10.2022 13:41