noi n的阶乘 大整数

#include<cstdio>
#include<cstring>
#define q 200000
int main()
{
    int n,a[q],i,j,k,m;
    while(scanf("%d",&n)!=EOF)
    {
        k=1;
       memset(a,0,sizeof(a));///把数组清0
        a[1] = 1;
        for (i=1; i<=n; i++)
        {
            for (m=1; m<=k; m++)///将每一位乘i，之后再将进行进位
                a[m] = a[m]*i;
            for(j=1; j<=k+10; j++)
                while(a[j]>9)///进位操作
                {
                    a[j+1] += a[j]/10;
                    a[j] = a[j]%10;
                    j=j+1;
                    k = j;
                }
        }
        for(i=k; i>0; i--)
            printf("%d",a[i]);
        printf("\n");
    }
    return 0;
}