模板为转载，原模版在https://paste.ubuntu.com/p/7VKYzpC7dn/
const double PI = acos(-1.0);
struct Complex{
double x,y;
Complex(double _x = 0.0,double _y = 0.0){
x = _x;
y = _y;
}
Complex operator-(const Complex &b)const{
return Complex(x - b.x,y - b.y);
}
Complex operator+(const Complex &b)const{
return Complex(x + b.x,y + b.y);
}
Complex operator*(const Complex &b)const{
return Complex(x*b.x - y*b.y,x*b.y + y*b.x);
}
};
void change(Complex y[],int len){
int i,j,k;
for(int i = 1,j = len/2;i<len-1;i++){
if(i < j) swap(y[i],y[j]);
k = len/2;
while(j >= k){
j = j - k;
k = k/2;
}
if(j < k) j+=k;
}
}
void fft(Complex y[],int len,int on){
change(y,len);
for(int h = 2;h <= len;h<<=1){
Complex wn(cos(on*2*PI/h),sin(on*2*PI/h));
for(int j = 0;j < len;j += h){
Complex w(1,0);
for(int k = j;k < j + h/2;k++){
Complex u = y[k];
Complex t = w*y[k + h/2];
y[k] = u + t;
y[k + h/2] = u - t;
w = w*wn;
}
}
}
if(on == -1){
for(int i = 0;i < len;i++){
y[i].x /= len;
}
}
}
class BigInt
{
#define Value(x, nega) ((nega) ? -(x) : (x))
#define At(vec, index) ((index) < vec.size() ? vec[(index)] : 0)
static int absComp(const BigInt &lhs, const BigInt &rhs)
{
if (lhs.size() != rhs.size())
return lhs.size() < rhs.size() ? -1 : 1;
for (int i = lhs.size() - 1; i >= 0; --i)
if (lhs[i] != rhs[i])
return lhs[i] < rhs[i] ? -1 : 1;
return 0;
}
using Long = long long;
const static int Exp = 9;
const static Long Mod = 1000000000;
mutable std::vector<Long> val;
mutable bool nega = false;
void trim() const
{
while (val.size() && val.back() == 0)
val.pop_back();
if (val.empty())
nega = false;
}
int size() const { return val.size(); }
Long &operator[](int index) const { return val[index]; }
Long &back() const { return val.back(); }
BigInt(int size, bool nega) : val(size), nega(nega) {}
BigInt(const std::vector<Long> &val, bool nega) : val(val), nega(nega) {}
public:
friend std::ostream &operator<<(std::ostream &os, const BigInt &n)
{
if (n.size())
{
if (n.nega)
putchar('-');
for (int i = n.size() - 1; i >= 0; --i)
{
if (i == n.size() - 1)
printf("%lld", n[i]);
else
printf("%0*lld", n.Exp, n[i]);
}
}
else
putchar('0');
return os;
}
friend BigInt operator+(const BigInt &lhs, const BigInt &rhs)
{
BigInt ret(lhs);
return ret += rhs;
}
friend BigInt operator-(const BigInt &lhs, const BigInt &rhs)
{
BigInt ret(lhs);
return ret -= rhs;
}
BigInt(Long x = 0)
{
if (x < 0)
x = -x, nega = true;
while (x >= Mod)
val.push_back(x % Mod), x /= Mod;
if (x)
val.push_back(x);
}
BigInt(const char *s)
{
int bound = 0, pos;
if (s[0] == '-')
nega = true, bound = 1;
Long cur = 0, pow = 1;
for (pos = strlen(s) - 1; pos >= Exp + bound - 1; pos -= Exp, val.push_back(cur), cur = 0, pow = 1)
for (int i = pos; i > pos - Exp; --i)
cur += (s[i] - '0') * pow, pow *= 10;
for (cur = 0, pow = 1; pos >= bound; --pos)
cur += (s[pos] - '0') * pow, pow *= 10;
if (cur)
val.push_back(cur);
}
BigInt &operator=(const char *s){
BigInt n(s);
*this = n;
return n;
}
BigInt &operator=(const Long x){
BigInt n(x);
*this = n;
return n;
}
friend std::istream &operator>>(std::istream &is, BigInt &n){
string s;
is >> s;
n=(char*)s.data();
return is;
}
BigInt &operator+=(const BigInt &rhs)
{
const int cap = std::max(size(), rhs.size()) + 1;
val.resize(cap);
int carry = 0;
for (int i = 0; i < cap - 1; ++i)
{
val[i] = Value(val[i], nega) + Value(At(rhs, i), rhs.nega) + carry, carry = 0;
if (val[i] >= Mod)
val[i] -= Mod, carry = 1;
else if (val[i] < 0)
val[i] += Mod, carry = -1;
}
if ((val.back() = carry) == -1) //assert(val.back() == 1 or 0 or -1)
{
nega = true, val.pop_back();
bool tailZero = true;
for (int i = 0; i < cap - 1; ++i)
{
if (tailZero && val[i])
val[i] = Mod - val[i], tailZero = false;
else
val[i] = Mod - 1 - val[i];
}
}
trim();
return *this;
}
friend BigInt operator-(const BigInt &rhs)
{
BigInt ret(rhs);
ret.nega ^= 1;
return ret;
}
BigInt &operator-=(const BigInt &rhs)
{
rhs.nega ^= 1;
*this += rhs;
rhs.nega ^= 1;
return *this;
}
friend BigInt operator*(const BigInt &lhs, const BigInt &rhs)
{
int len=1;
BigInt ll=lhs,rr=rhs;
ll.nega = lhs.nega ^ rhs.nega;
while(len<2*lhs.size()||len<2*rhs.size())len<<=1;
ll.val.resize(len),rr.val.resize(len);
Complex x1[len],x2[len];
for(int i=0;i<len;i++){
Complex nx(ll[i],0.0),ny(rr[i],0.0);
x1[i]=nx;
x2[i]=ny;
}
fft(x1,len,1);
fft(x2,len,1);
for(int i = 0 ; i < len; i++)
x1[i] = x1[i] * x2[i];
fft( x1 , len , -1 );
for(int i = 0 ; i < len; i++)
ll[i] = int( x1[i].x + 0.5 );
for(int i = 0 ; i < len; i++){
ll[i+1]+=ll[i]/Mod;
ll[i]%=Mod;
}
ll.trim();
return ll;
}
friend BigInt operator*(const BigInt &lhs, const Long &x){
BigInt ret=lhs;
bool negat = ( x < 0 );
Long xx = (negat) ? -x : x;
ret.nega ^= negat;
ret.val.push_back(0);
ret.val.push_back(0);
for(int i = 0; i < ret.size(); i++)
ret[i]*=xx;
for(int i = 0; i < ret.size(); i++){
ret[i+1]+=ret[i]/Mod;
ret[i] %= Mod;
}
ret.trim();
return ret;
}
BigInt &operator*=(const BigInt &rhs) { return *this = *this * rhs; }
BigInt &operator*=(const Long &x) { return *this = *this * x; }
friend BigInt operator/(const BigInt &lhs, const BigInt &rhs)
{
static std::vector<BigInt> powTwo{BigInt(1)};
static std::vector<BigInt> estimate;
estimate.clear();
if (absComp(lhs, rhs) < 0)
return BigInt();
BigInt cur = rhs;
int cmp;
while ((cmp = absComp(cur, lhs)) <= 0)
{
estimate.push_back(cur), cur += cur;
if (estimate.size() >= powTwo.size())
powTwo.push_back(powTwo.back() + powTwo.back());
}
if (cmp == 0)
return BigInt(powTwo.back().val, lhs.nega ^ rhs.nega);
BigInt ret = powTwo[estimate.size() - 1];
cur = estimate[estimate.size() - 1];
for (int i = estimate.size() - 1; i >= 0 && cmp != 0; --i)
if ((cmp = absComp(cur + estimate[i], lhs)) <= 0)
cur += estimate[i], ret += powTwo[i];
ret.nega = lhs.nega ^ rhs.nega;
return ret;
}
friend BigInt operator/(const BigInt &num,const Long &x){
bool negat = ( x < 0 );
Long xx = (negat) ? -x : x;
BigInt ret;
Long k = 0;
ret.val.resize( num.size() );
ret.nega = (num.nega ^ negat);
for(int i = num.size() - 1 ;i >= 0; i--){
ret[i] = ( k * Mod + num[i]) / xx;
k = ( k * Mod + num[i]) % xx;
}
ret.trim();
return ret;
}
bool operator==(const BigInt &rhs) const
{
return nega == rhs.nega && val == rhs.val;
}
bool operator!=(const BigInt &rhs) const { return nega != rhs.nega || val != rhs.val; }
bool operator>=(const BigInt &rhs) const { return !(*this < rhs); }
bool operator>(const BigInt &rhs) const { return !(*this <= rhs); }
bool operator<=(const BigInt &rhs) const
{
if (nega && !rhs.nega)
return true;
if (!nega && rhs.nega)
return false;
int cmp = absComp(*this, rhs);
return nega ? cmp >= 0 : cmp <= 0;
}
bool operator<(const BigInt &rhs) const
{
if (nega && !rhs.nega)
return true;
if (!nega && rhs.nega)
return false;
return (absComp(*this, rhs) < 0) ^ nega;
}
void swap(const BigInt &rhs) const
{
std::swap(val, rhs.val);
std::swap(nega, rhs.nega);
}
};