[迁移]高精度数模板(包含运算符重载，C++实现)

#include <cstdio>
#include <cstring>
#include <iostream>
#include <cmath>
using namespace std;
const int MAXN = 4000;
struct BIGNUM
{
    int len, s[MAXN];
    BIGNUM()
    {
        memset(s, 0, sizeof(s));
        len = 1;
    }
    BIGNUM operator=(const char *num)
    {
        len = strlen(num);
        for (int i = 0; i < len; ++i)
            s[i] = num[len - i - 1] - '0';
        return *this;
    }
    BIGNUM operator=(const int num)
    {
        char a[MAXN];
        sprintf(a, "%d", num);
        *this = a;
        return *this;
    }
    BIGNUM(const int num) { *this = num; }
    BIGNUM(const char *num) { *this = num; }
    BIGNUM operator+(const BIGNUM &a)
    {
        BIGNUM c;
        c.len = max(len, a.len) + 1;
        for (int i = 0, x = 0; i < c.len; ++i)
        {
            c.s[i] = s[i] + a.s[i] + x;
            x = c.s[i] / 10;
            c.s[i] = c.s[i] % 10;
        }
        if (c.s[c.len - 1] == 0)
            --c.len;
        return c;
    }
    BIGNUM operator+=(const BIGNUM &a)
    {
        *this = *this + a;
        return *this;
    }
    BIGNUM operator*(const BIGNUM &x)
    {
        BIGNUM c;
        c.len = len + x.len;
        for (int i = 0; i < len; ++i)
        {
            for (int j = 0; j < x.len; ++j)
            {
                c.s[i + j] += s[i] * x.s[j];
                c.s[i + j + 1] += c.s[i + j] / 10;
                c.s[i + j] %= 10;
            }
        }
        if (c.s[c.len - 1] == 0)
            --c.len;
        return c;
    }
    BIGNUM operator*=(const BIGNUM &a)
    {
        *this = *this * a;
        return *this;
    }
    bool operator<(const BIGNUM &x) const
    {
        if (len != x.len)
            return len < x.len;
        for (int i = len - 1; i >= 0; --i)
        {
            if (s[i] != x.s[i])
                return s[i] < x.s[i];
        }
        return false;
    }
    bool operator>(const BIGNUM &x) const { return x < *this; }
    bool operator<=(const BIGNUM &x) const { return !(x < *this); }
    bool operator>=(const BIGNUM &x) const { return !(*this < x); }
    bool operator==(const BIGNUM &x) const { return !(x < *this || *this < x); }
    bool operator!=(const BIGNUM &x) const { return x < *this || *this < x; }
};
ostream &operator<<(ostream &out, const BIGNUM &x)
{
    for (int i = x.len - 1; i >= 0; --i)
        cout << x.s[i];
    return out;
}
istream &operator>>(istream &in, BIGNUM &x)
{
    char num[MAXN];
    in >> num;
    x = num;
    return in;
}
BIGNUM f[5001];
int main()
{
    int n;
    BIGNUM m, sum = 0, num = 1;
    cin >> n >> m;
    for (int i = 1; i <= n; ++i)
    {
        num *= i;
        sum += num;
    }
    if (sum > m)
        cout << "yes" << endl;
    else
        cout << "no" << endl;
    return 0;
}