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Prime Factorization

rey9 (24)
hello guys. I need help. I am making a program that will output all pime factors of an integer.
This is my code

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#include<iostream>
#include<cmath>
using namespace std;

bool isPrime(int n)
{
	if(n < 2)
	    return false;
	for(int m = 2 ; m <= sqrt(n) ; m++)	
	{
	   if (n % m == 0)		   	
		return false;			
	}
	return true;				


}
int main()
{
    int x = 32, y, p;
    cout << x << " = ";
    for(y = 2; y <= x/2; y++){
       p=x%y;
       if(isPrime(p) && p!=0)
          cout << p << " x ";
    }

    return 0;
}


my output is this

32 = 2 x 2 x 2 x 5 x 2 x 2 x


it should be like this

32 = 2 x 2 x 2 x 2 x 2
Zephilinox (595)
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#include<iostream>
#include<cmath>

bool isPrime(int);

bool isPrime(int n)
{
	if(n < 2)
        return false;

	for(int m = 2; m <= sqrt(n); m++)
	{
        if (n % m == 0)
            return false;
	}

	return true;
}

int main()
{
    int x = 32;

    std::cout << x << " = ";

    if (isPrime(x)) std::cout << x << std::endl;
    else
    {
        for (int y = 1; y < x; y++)
        {
            if (isPrime(y) && x % y == 0)
            {
                x /= y;
                std::cout << y << " * ";
                y--; //counter-act y++
            }
            if (x == 2) std::cout << 2 << std::endl;
        }
    }
    return 0;
}
}
Last edited on
rey9 (24)
thank you sir for the help.
i made another code:


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#include <iostream>
using namespace std;

int main()
{
    long long int num;
    while(cin >> num){

    if(num<=1)
        cout << num << " is unexpected input";
    else
        cout << num << " = ";

    for (int i=2; i <= num; i++)
    {
        while(num % i == 0)
        {
            num /= i;
            cout << i;
        cout << " x ";
    }
    }

cout << endl;
}

return 0;
}


and my input is this

345
-2
32
4294967295


and the output is this

345
345 = 3 x 5 x 23 x
-2
-2 is unexpected input
32
32 = 2 x 2 x 2 x 2 x 2 x
4294967295
4294967295 = 3 x 5 x 17 x 257 x 65537 x


my problem now is the extra 'x' at the end of each equation. How will I remove them?
Zephilinox (595)
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#include <iostream>

int main()
{
    long long int num;
    while(std::cin >> num)
    {
        if(num <= 1)
        {
            std::cout << num << " is unexpected input" << std::endl;
            continue;
        }

        std::cout << num << " = ";

        for (int i = 2; i <= num; i++)
        {
            while(num % i == 0)
            {
                num /= i;
                std::cout << i;

                if (num > 1)
                    std::cout << " x ";
                else
                    std::cout << std::endl;
            }
        }
    }
    return 0;
}
rey9 (24)
Thank you very much sir for the help!!
Zephilinox (595)
no problem :]
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