大佬求助，全wa了

#include <iostream>
#include <string>
using namespace std;

int mul[1010],sum[1010];

void addBIG(int x[], int y[], int z[])
{
    z[0] = max(x[0],y[0]);
    for(int i = 1;i <= z[0];i++)
    {
        z[i] = x[i] + y[i];
    }
    for(int i = 1;i <= z[0];i++)
    {
        z[i + 1] += z[i] / 10;
        z[i] %= 10;
        if(z[z[0] + 1] > 0) z[0]++;
    }
}

void i2BIG(int n, int a[]) 
{
    int la = 0;
    while (n > 0)
    {
          la++;
          a[la] = n % 10;
          n /= 10;
    }
    if (la == 0) la++;
    a[0] = la;  
}

void printBIG(int a[]) 
{
    int la = a[0];  
    for (int i = la; i >= 1; i--) 
    {
        cout << a[i];
    }
    cout << endl;
}

void mulBIG(int x[], int y, int z[])
{
    z[0] = x[0];
    for (int i = 1; i <= z[0]; i++)
        z[i] = x[i] * y;
    for (int i = 1; i <= z[0]; i++) 
    {
        z[i + 1] += z[i] / 10;
        z[i] %= 10;
        if (z[z[0] + 1] > 0) z[0]++;
    }
}

void aaa(int n)
{
    mul[1] = 1;
    mul[0] = 1;
    for(int i = 1;i <= n;i++)
    {
        mulBIG(mul,i,mul);
    }
}

int main()
{
    int x;
    cin >> x;
    for(int i = 1;i <= x;i++)
    {
        aaa(i);
        addBIG(sum,mul,sum);
    }
    printBIG(sum);
    return 0;
}