阶乘之和加强版

#include<stdio.h>
#include<string.h>
int sum[500], sum1[500];
int a[500], b[500],c[500],d[500];
int main(void)
{
    int n,len_a,len_b = 1,s = 0;

    scanf("%d", &n);
    for (int i = 1; i <= n; i++)
    {
        s = 0;
        len_b = 1;
        b[1] = 1;
        for (int j = 1; j <= i; j++)
        {
             len_a = 1;
            int m = j;
            while (m > 0)
            {
                a[len_a++] = m % 10;
                m /= 10;
            }
            for (int x = 1; x <= len_a; x++)
            {
                for (int y = 1; y <= len_b; y++)
                {
                    c[x + y - 1] += a[x] * b[y];
                }
            }
            for (int x = 1; x <= len_a + len_b; x++)
            {
                if (c[x] > 9)
                {
                    c[x + 1] += c[x] / 10;
                    c[x] %= 10;
                }
            }
             s = len_a + len_b;
            for (int x = s; c[x] == 0; x--) s--;
            for (int x = 1; x <= s; x++)
            {
                b[x] = c[x];
            }
            len_b = s;
            memset(c, 0, sizeof(c));
            memset(a, 0, sizeof(a));
        }

        for (int i = 1; i <= s; i++)
        {
            d[i] += b[i];
        }

        for (int i = 1; i <= s; i++)
        {
            if (d[i] > 9)
            {
                d[i + 1] += d[i] / 10;
                d[i] %= 10;
                if (i == s)
                    s++;
            }
        }

        for (int i = s; i >= 1; i--)
            if (d[i] == 0)
            {
                s--;
            }
            else
                break;

        memset(b, 0, sizeof(b));
    }
    for (int i = s; i >= 1; i--)
    {
        printf("%d", d[i]);
    }
}