[C언어 #19] 소인수 분해

C언어 소인수 분해 (Factorization)

ex. 18 소인수 분해; 입력한 숫자 소인수 분해

 

 

 

Factoring 18

 

/* Factorization */
#include <stdio.h>
 
int main() {
    int num = 18;
    int a[18];
    int count = 0;
 
    while (num != 1) {
        for (int i = 2; i <= num; i++) {
            if (num % i == 0) {
                a[count] = i;
                count++;
                num = num/i;
                break;
            }
        }
    }
 
    if (count == 1) {
        printf("%d is prime.\n", num);
    } else {
        for (int i = 0; i < count-1; i++) {
            printf("%d x ", a[i]);
        }
        printf("%d\n", a[count-1]);
    }
    return 0;
}

 

 

Factoring input number

 

/* Factorization */
#include <stdio.h>
 
/* Get input number */
int getInputNumber() {
    int input = 0;
    printf("Input an integer: ");
    scanf("%d", &input);
    return input;
}
 
/* Print result */
void print(int orgNum, int count, const int a[]) {
    if (count == 1) {
        printf("%d is prime.\n", orgNum);
    } else {
        printf("%d = ", orgNum);
        for (int i = 0; i < count-1; i++) {
            printf("%d x ", a[i]);
        }
        printf("%d\n", a[count-1]);
    }
}
 
int main() {
    int orgNum = getInputNumber();
    int num = orgNum;
    int a[num];
    int count = 0;
    while (num != 1) {
        for (int i = 2; i <= num; i++) {
            if (num % i == 0) {
                a[count] = i;
                count++;
                num = num/i;
                break;
            }
        }
    }
    print(orgNum, count, a); 
    return 0;
}