www.pudn.com > miracl.zip > BRUTE.CPP

/* 
 *   Program to factor numbers using brute force. 
 *   Copyright (c) 1988-1997 Shamus Software Ltd. 
 * 
 *   Requires: big.cpp 
 */ 
 
#include  
#include  
 
using namespace std; 
 
#define LIMIT 10000 
 
#ifndef MR_NOFULLWIDTH 
Miracl precision=50; 
#else 
Miracl precision(50,MAXBASE); 
#endif 
 
int main() 
{ 
    int n,p; 
    Big x; 
    miracl *mr=&precision; 
    gprime(LIMIT); /* generate all primes < LIMIT */ 
    cout << "input number to be factored\n"; 
    cin >> x; 
    n=0; 
    p=mr->PRIMES[0]; 
    cout << "factors are "; 
    forever 
    { /* try division by each prime */ 
        if (x%p==0) 
        { /* factor found */ 
            x/=p; 
            cout << "\nprime factor     " << p << flush; 
            if (x==1) return 0; 
            continue; 
        } 
        if ((x/p)<=p) 
        { /* must be prime */ 
            cout << "\nprime factor     " << x << "\n";  
            return 0; 
        } 
        p=mr->PRIMES[++n]; 
        if (p==0) break; 
    } 
    if (prime(x)) cout << "\nprime factor     " << x << "\n"; 
    else          cout << "\ncomposite factor " << x << "\n"; 
    return 0; 
}