封装高精板子

#include<bits/stdc++.h>
using namespace std;
const int maxn=5005;
struct bign 
{
    int len, s[MAXN];
    bign () 
    {
        memset(s, 0, sizeof(s));
        len = 1;
    }
    bign (int num) 
    {
        *this = num;
    }
    bign (const char *num) 
    {
        *this = num;
    }
    bign operator = (const int num) 
    {
        char s[MAXN];
        sprintf(s, "%d", num);
        *this = s;
        return *this;
    }
    bign operator = (const char *num) 
    {
        for(int i = 0; num[i] == '0'; num++) ;
        len = strlen(num);
        for(int i = 0; i < len; i++) s[i] = num[len-i-1] - '0';
        return *this;
    }
    bign operator + (const bign &b) const 
    {
        bign c;
        c.len = 0;
        for(int i = 0, g = 0; g || i < max(len, b.len); i++) 
        {
            int x = g;
            if(i < len) x += s[i];
            if(i < b.len) x += b.s[i];
            c.s[c.len++] = x % 10;
            g = x / 10;
        }
        return c;
    }
    void clean() 
    {
        while(len > 1 && !s[len-1]) len--;
    }
    bign operator * (const bign &b) 
    {
        bign c;
        c.len = len + b.len;
        for(int i = 0; i < len; i++) 
        {
            for(int j = 0; j < b.len; j++) 
            {
                c.s[i+j] += s[i] * b.s[j];
            }
        }
        for(int i = 0; i < c.len; i++)
        {
            c.s[i+1] += c.s[i]/10;
            c.s[i] %= 10;
        }
        c.clean();
        return c;
    }
    string str() const 
    {
        string res = "";
        for(int i = 0; i < len; i++) res = char(s[i]+'0')+res;
        return res;
    }
};
ostream& operator << (ostream &out, const bign &x) 
{
    out << x.str();
    return out;
}
bign d[2001];
int main()
{
	int n;
	cin>>n;
	for(int i=1;i<=n;++i)
	cin>>d[i];
	cout<<(d[1]*d[2])*(d[1]+d[2]);
}
//是这么用的吗（？）超的别人的使用🤣前记得👉打括号🤡