prime factorization trial division, C++ (gcc)

prime factorization trial division

#include<bits/stdc++.h>
#define LL long long
#define MAXN 1000000000
using namespace std;
inline void speed(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
}
vector <bool> isprime(MAXN,1);
vector <int> primes;
inline void pre(){
	for(int i=2;i*i<MAXN;i++){
        if(isprime[i]){
            primes.push_back(i);
            for(int j=i*i;j<MAXN;j+=i){
                isprime[j]=0;
            }
        }
	}
    for(int i=2;i<MAXN;i++){
        if(isprime[i]){
                primes.push_back(i);
        }
    }
}
int main() {
	speed();
	pre();
	LL n;
	//cin>>n;
    //for(int i=0;i<100;i++)cout<<primes[i]<<" ";
	/*while ( n != 0 ) {
        for(int i=0;i<primes.size();i++){
            int pw=0;
            //cout<<n<<" "<<primes[i]<<endl;
            while(n%primes[i]==0){
                if(n==1)break;
                //cout<<n<<" "<<primes[i]<<endl;
                n=n/primes[i];
                pw++;
            }
            if(pw>0){
                    cout<<primes[i]<<"^"<<pw<<" ";
            }
            if(n==1){
                break;
            }
        }
        if(n!=1){
                cout<<n<<"^"<<1;
        }
		cout<<"\n";
        cin>>n;
	}*/
	return 0;
}


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