팩토리얼 구하기 더블릿

#include <stdio.h>
#define ten 10
 
int arr[1000000] = { 0 };
int cnt = 1;
 
int main() {
    int n,up=0;
    scanf("%d", &n);
 
    arr[1] = 1;
    for (int i = 2; i <= n; i++) {
        for (int j = 1; j <= cnt; j++) {
            arr[j] = (arr[j] * i + up);
            up = (arr[j] / ten);
            arr[j] %= ten;            
        }
        while (up != 0) {
            arr[++cnt] = up % ten;
            up /= ten;            
        }
    }
 
    for (int i = cnt; i >= 1; i--) {
        printf("%d", arr[i]);
    }
}