高精度真的是我见过的比较恶心的模拟之一了。

class HugeInt
{
	friend ostream& operator<<(ostream&, const HugeInt&);
public:
	static const int digits = 30;
	HugeInt(long = 0); 
	HugeInt(const char*); 

	HugeInt operator+(const HugeInt&) const;
	HugeInt operator+(int) const;
	HugeInt operator+(const char*) const;
	HugeInt operator-(const HugeInt&) const;
	HugeInt operator*(const HugeInt&) const;
	HugeInt operator/(const HugeInt&) const;
	bool operator<(const HugeInt&) const;
	bool operator<=(const HugeInt&) const;
	bool operator>(const HugeInt&) const;
	bool operator>=(const HugeInt&) const;
	bool operator==(const HugeInt&) const;
	bool operator!=(const HugeInt&) const;

	int getLength() const;
private:
	vector<int> integer=vector<int>(digits,0);
}; 

void add(const vector<int> a, const vector<int> b,vector<int>& c) {
	for (int i = 0; i < HugeInt::digits; ++i) {
		c[i] += a[i] + b[i];
		if (c[i] / 10) {
			c[i + 1] += 1;
			c[i] -= 10;
		}
	}
}
void sub(const vector<int> a, const vector<int> b, vector<int>& c) {
	for (int i = 0; i < HugeInt::digits; ++i) {
		c[i] += a[i] - b[i];
		if (c[i] < 0) {
			c[i + 1] -= 1;
			c[i] += 10;
		}
	}
}
void mul(const vector<int> a, const vector<int> b, vector<int>& c) {
	for (int i = 0; i < HugeInt::digits; ++i) {
		for (int j = 0; j <= i; ++j) c[i] += a[j] * b[i - j];

		if (c[i] / 10) {
			c[i + 1] += c[i] / 10;
			c[i] %= 10;
		}
	}
}
inline bool greater_eq(const vector<int> a,const vector<int> b, int last_dg, int len) {
	if (a[last_dg + len] != 0) return true;
	for (int i = len - 1; i >= 0; --i) {
		if (a[last_dg + i] > b[i]) return true;
		if (a[last_dg + i] < b[i]) return false;
	}
	return true;
}
void div(const vector<int> a,const vector<int> b,vector<int>& c) {
	vector<int> d(HugeInt::digits, 0);
	int a_len, b_len;
	for (a_len = HugeInt::digits-1; a_len > 0; --a_len)
		if (a[a_len - 1] != 0) break;
	for (b_len = HugeInt::digits - 1; b_len > 0; --b_len)
		if (b[b_len - 1] != 0) break;

	for (int i = 0; i < a_len; ++i) d[i] = a[i];
	for (int i = a_len - b_len; i >= 0; --i) {
		while (greater_eq(d, b, i, b_len)) {
			for (int j = 0; j < b_len; ++j) {
				d[i + j] -= b[j];
				if (d[i + j] < 0) {
					d[i + j + 1] -= 1;
					d[i + j] += 10;
				}
			}
			c[i] += 1;
		}
	}
}


ostream& operator<<(ostream& out, const HugeInt& num) {
	bool flag = 0;
	for (int i = HugeInt::digits - 1; i >= 0; i--) {
		if (num.integer[i])flag = 1;
		if (flag) {
			out << num.integer[i];
		}
	}
	if (!flag)out << 0;
	return out;
}
HugeInt::HugeInt(long a) {
	int cnt = 0;
	while (a) {
		integer[cnt++] = (short)(a % 10);
		a /= 10;
	}
}
HugeInt::HugeInt(const char* s) {
	int len = strlen(s);
	for (int i = 0; i < len; ++i) {
		integer[len - i - 1] = (short)(s[i] - '0');
	}
}
bool HugeInt::operator<(const HugeInt& num) const {
	int len_1 = 0, len_2 = 0;
	for (int i = HugeInt::digits - 1; i >= 0; i--) {
		if (this->integer[i]) {
			len_1 = i + 1; 
			break;
		}
	}
	for (int i = HugeInt::digits - 1; i >= 0; i--) {
		if (this->integer[i]) {
			len_2 = i + 1; 
			break;
		}
	}
	if (len_1 < len_2)return 1;
	else if (len_1 > len_2)return 0;
	else {
		for (int i = len_1 - 1; i >= 0; i--) {
			if (this->integer[i] < num.integer[i])return 1;
			else if (this->integer[i] < num.integer[i])return 0;
		}
		return 0;
	}
}
bool HugeInt::operator<=(const HugeInt& num) const {
	int len_1 = 0, len_2 = 0;
	for (int i = HugeInt::digits - 1; i >= 0; i--) {
		if (this->integer[i]) {
			len_1 = i + 1;
			break;
		}
	}
	for (int i = HugeInt::digits - 1; i >= 0; i--) {
		if (this->integer[i]) {
			len_2 = i + 1;
			break;
		}
	}
	if (len_1 < len_2)return 1;
	else if (len_1 > len_2)return 0;
	else {
		for (int i = len_1 - 1; i >= 0; i--) {
			if (this->integer[i] < num.integer[i])return 1;
			else if (this->integer[i] < num.integer[i])return 0;
		}
		return 1;
	}
}
bool HugeInt::operator>(const HugeInt& num) const {
	return !(*this <= num);
}
bool HugeInt::operator>=(const HugeInt& num) const {
	return !(*this < num);
}
bool HugeInt::operator==(const HugeInt& num) const {
	for (int i = 0; i < HugeInt::digits; i++) {
		if (this->integer[i] != num.integer[i])return 0;
	}
}
bool HugeInt::operator!=(const HugeInt& num) const {
	return !(*this == num);
}
HugeInt HugeInt::operator-(const HugeInt& num) const {
	HugeInt tmp;
	sub(this->integer, num.integer, tmp.integer);
	return tmp;
}
HugeInt HugeInt::operator+(const HugeInt& num) const{
	HugeInt tmp;
	add(this->integer, num.integer, tmp.integer);
	return tmp;
}
HugeInt HugeInt::operator+(int num)const {
	HugeInt tmp;
	HugeInt n((long)num);
	add(this->integer, n.integer, tmp.integer);
	return tmp;
}
HugeInt HugeInt::operator+(const char* num)const {
	HugeInt tmp;
	HugeInt n(num);
	add(this->integer, n.integer, tmp.integer);
	return tmp;
}
HugeInt HugeInt::operator*(const HugeInt& num) const {
	HugeInt tmp;
	mul(this->integer, num.integer, tmp.integer);
	return tmp;
}
HugeInt HugeInt::operator/(const HugeInt & num) const {
	HugeInt tmp;
	div(this->integer, num.integer, tmp.integer);
	return tmp;
}
int HugeInt::getLength() const {
	for (int i = this->digits - 1; i >= 0; i--) {
		if (this->integer[i])return i + 1;
	}
}