c - 质因数分解

Question

所以我的教授让我们编写一个程序，对用户给出的数字进行质因分解。并以指数形式给出答案。因此，如果您的号码是 96，我会像这样列出程序 2 x 2 x 2 x 2 x 3。他希望我们像这样列出程序。 2^5 x 3^1。我该如何去做呢？

#include <stdio.h>

int main() {

    int i, n;

    // Get the user input.
    printf("Please enter a number.\n");
    scanf("%d", &n);

    // Print out factorization
    printf("The prime factorization of %d is ", n);

    // Loop through, finding prime factors.
    int cur_factor = 2;
    while (cur_factor < n) {

        // Found a factor.
        if (n%cur_factor == 0) {
            printf("%d x ", cur_factor);
            n = n/cur_factor;
        }

        // Going to the next possible factor.
        else
            cur_factor++;
    }

    // Prints last factor.
    printf("%d.\n", cur_factor);

    return 0;
}

Answer 1

您可以通过在 if block 内引入 while 循环来实现此目的，计算当前素因数的幂并在此处打印出来。

#include <stdio.h>

int main()
{

    int n;

    // Get the user input.
    printf( "Please enter a number.\n" );
    scanf( "%d", &n );

    // Print out factorization
    printf( "The prime factorization of %d is ", n );

    // Loop through, finding prime factors.
    int cur_factor = 2;
    while ( cur_factor < n )
    {

        // Found a factor.
        if ( n % cur_factor == 0 )
        {
            int expo = 0;
            while ( n % cur_factor == 0 )
            {
                n = n / cur_factor;
                expo++;
            }
            printf( "%d^%d", cur_factor, expo );
            if ( n != 1 )
            {
                printf( " x " );
            }
        }

        // Going to the next possible factor.
        cur_factor++;
    }

    // Prints last factor.
    if ( n != 1 )
    {
        printf( "%d^1.\n", cur_factor );
    }
    return 0;
}