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| #include <bits/stdc++.h>
using namespace std;
struct cmplx
{
double r, i;
cmplx operator+(cmplx b) { return {r + b.r, i + b.i}; }
cmplx operator-(cmplx b) { return {r - b.r, i - b.i}; }
cmplx operator*(cmplx b) { return {r * b.r - i * b.i, r * b.i + i * b.r}; }
};
struct bigint
{
private:
string s;
int sign;
public:
bigint() : sign(1){};
bigint(long long v) : s(to_string(v)), sign(1)
{
reverse(s.begin(), s.end());
if (s.back() == '-')
sign = -1, s.pop_back();
for (auto &i : s)
i -= '0';
}
bigint abs() const
{
bigint ans = *this;
ans.sign = 1;
return ans;
}
friend ostream &operator<<(ostream &o, bigint a)
{
if (a.sign == -1)
o << '-';
for (int i = (int)size(a.s) - 1; i >= 0; i--)
o << char(a.s[i] + '0');
return o;
}
friend istream &operator>>(istream &i, bigint &a)
{
i >> a.s;
reverse(a.s.begin(), a.s.end());
if (a.s.back() == '-')
a.sign = -1, a.s.pop_back();
for (auto &i : a.s)
{
assert(isdigit(i));
i -= '0';
}
while (a.s.back() == 0 && size(a.s) > 1)
{
a.s.pop_back();
}
return i;
}
friend bool operator==(const bigint &a, const bigint &b) { return a.sign == b.sign && a.s == b.s; }
friend bool operator!=(const bigint &a, const bigint &b) { return !(a == b); }
friend bool operator<(const bigint &a, const bigint &b)
{
if (a.sign < 0 && b.sign > 0)
return true;
if (a.sign > 0 && b.sign < 0)
return false;
if (size(a.s) != size(b.s))
return (size(a.s) < size(b.s)) && (a.sign == 1);
for (int i = (int)size(a.s) - 1; i >= 0; i--)
{
if (a.s[i] == b.s[i])
continue;
return (a.s[i] < b.s[i]) && (a.sign == 1);
}
return false;
}
friend bool operator>(const bigint &a, const bigint &b) { return b < a; }
bigint operator+() const { return *this; }
bigint operator-() const
{
bigint a = *this;
a.sign *= -1;
return a;
}
bigint &operator+=(const bigint &b)
{
size_t la = size(s), lb = size(b.s);
if (sign == b.sign)
{
s.resize(max(la, lb) + 1);
for (size_t i = 0; i < lb; i++)
{
s[i] += b.s[i];
}
for (size_t i = 0; i < size(s) - 1; i++)
{
s[i + 1] += char(s[i] / 10);
s[i] %= 10;
}
if (s.back() == 0)
s.pop_back();
return *this;
}
else
{
if (abs() == b.abs())
{
*this = bigint(0);
return *this;
}
if (abs() > b.abs())
{
for (size_t i = 0; i < lb; i++)
{
s[i] -= b.s[i];
if (s[i] < 0)
s[i] += 10, s[i + 1]--;
}
for (size_t i = lb; i < la - 1; i++)
{
if (s[i] < 0)
s[i] += 10, s[i + 1]--;
}
while (s.back() == 0 && size(s) > 1)
s.pop_back();
return *this;
}
else
{
sign *= -1;
s.resize(lb);
for (size_t i = 0; i < la; i++)
{
s[i] = b.s[i] - s[i];
if (s[i] < 0)
{
s[i] += 10;
s[i + 1]++;
if (i + 1 == la)
la++;
}
}
for (size_t i = la; i < lb; i++)
s[i] = b.s[i];
while (s.back() == 0 && size(s) > 1)
s.pop_back();
return *this;
}
}
}
bigint &operator-=(const bigint &b) { return *this += -b; }
bigint &operator*=(const bigint &b)
{
auto fft = [](vector<cmplx> &p, int g = 1) -> void
{
int n = (int)size(p), lg = __lg(n) - 1;
if (n == 1)
return;
const double pi = acos(-1);
vector<int> r(n);
for (int i = 0; i < n; i++)
{
r[i] = r[i >> 1] >> 1 | ((i & 1) << lg);
if (i < r[i])
swap(p[i], p[r[i]]);
}
for (int wid = 2; wid <= n; wid <<= 1)
{
cmplx w = {cos(2 * pi / wid * g), sin(2 * pi / wid * g)};
for (int l = 0; l < n; l += wid)
{
cmplx wi = {1, 0};
for (int i = l; i < l + wid / 2; i++, wi = w * wi)
{
cmplx x = p[i], y = p[i + wid / 2];
p[i] = x + wi * y;
p[i + wid / 2] = x - wi * y;
}
}
}
};
int n = int(size(s) + size(b.s)), lg = 0;
while (1 << lg < n)
{
lg++;
}
n = 1 << lg;
vector<cmplx> p(n);
for (int i = 0; i < n; i++)
{
p[i] = {double(i < int(size(s)) ? s[i] : 0), double(i < int(size(b.s)) ? b.s[i] : 0)};
}
fft(p);
for (int i = 0; i < n; i++)
{
p[i] = p[i] * p[i];
}
fft(p, -1);
s.resize(n);
int plus = 0;
for (int i = 0; i < n; i++)
{
int tmp = (int)round(p[i].i / (n << 1)) + plus;
s[i] = char(tmp % 10);
plus = tmp / 10;
}
while (s.back() == 0 && size(s) > 1)
s.pop_back();
sign *= b.sign;
if (s.back() == 0)
sign = 1;
return *this;
}
friend bigint operator+(const bigint &a, const bigint &b) { return bigint(a) += b; }
friend bigint operator-(const bigint &a, const bigint &b) { return bigint(a) -= b; }
friend bigint operator*(const bigint &a, const bigint &b) { return bigint(a) *= b; }
};
signed main()
{ bigint a,b;
return 0;
}
|
