Question

我创建了一个程序，它可以将给定的偶数分成两个素数的总和。

#include <iostream>
#include <stdio.h>
using namespace std;

int i(int x, int y)
{
    if (x > y)
    {
        if (x % y)
            return i(x, y + 1);
        else 
            return 0;
    }
    else
        return (x > 1);
}

int main()
{
    int a, b;

    do
    {
        cout << "Please input a positive even number: ";
        cin >> a;

        if (a % 2 == 0 && a >= 1)
        {
            for ( b = a/2; b > 1; b--)
            {
                if ((i(b, 2) && i(a-b, 2)) &&
                    printf("%i + %i\n", b, a-b));
            }
        }
        else if (a % 2 != 0 && a >= 1)
        {
            cout << a << "="<< a << endl;
        }
        else
            break;
    }
    while(a >= 4);

    return 0;
}

但是，我想将偶数分解为素因子乘以素因子，例如，12 = 2 * 2 * 3.修改程序的任何提示？谢谢你的帮助

Answer 1

检查出来：

// A function to print all prime factors of a given number n
void primeFactors(int n)
{
    // Print the number of 2s that divide n
    while (n%2 == 0){
        printf("%d ", 2);
        n = n/2;
    }

    // n must be odd at this point.  So we can skip one element (Note i = i +2)
    for (int i = 3; i <= sqrt(n); i = i+2){
        // While i divides n, print i and divide n
        while (n%i == 0){
            printf("%d ", i);
            n = n/i;
        }
    }

    // This condition is to handle the case when n is a prime number
    // greater than 2
    if (n > 2){
        printf ("%d ", n);
    }
}

来自http://www.geeksforgeeks.org/print-all-prime-factors-of-a-given-number/

Answer 2

这可能不是解决问题的最佳方法，但你可以选择或限制目的： - ）

   int r,q,a,i;
   cout << "Please input a positive even number: ";
   cin >> a;

   if (a % 2 == 0 && a >= 1)
   {
     for (i=2;i<=a;i++)
     {
         r=a%i;
         while (r==0)
         {
           cout<<i<<"*";
           q=q/i;
           r=q%i;    
         }
     }
   else
   {
    cout<<"Number is not even";
   }

C ++将偶数分解为素数因子

2 个答案: